diff --git a/code/Control/UserDefinedFormController.php b/code/Control/UserDefinedFormController.php
index 9979e0d7f..ef114865b 100644
--- a/code/Control/UserDefinedFormController.php
+++ b/code/Control/UserDefinedFormController.php
@@ -124,14 +124,14 @@ public function index(HTTPRequest $request = null)
     {
         $form = $this->Form();
         if ($this->Content && $form && !$this->config()->disable_form_content_shortcode) {
-            $hasLocation = stristr($this->Content, '$UserDefinedForm');
+            $hasLocation = stristr($this->Content ?? '', '$UserDefinedForm');
             if ($hasLocation) {
                 /** @see Requirements_Backend::escapeReplacement */
-                $formEscapedForRegex = addcslashes($form->forTemplate(), '\\$');
+                $formEscapedForRegex = addcslashes($form->forTemplate() ?? '', '\\$');
                 $content = preg_replace(
                     '/(<p[^>]*>)?\\$UserDefinedForm(<\\/p>)?/i',
-                    $formEscapedForRegex,
-                    $this->Content
+                    $formEscapedForRegex ?? '',
+                    $this->Content ?? ''
                 );
                 return [
                     'Content' => DBField::create_field('HTMLText', $content),
@@ -260,7 +260,7 @@ public function process($data, $form)
             $submittedField->Displayed = $field->isDisplayed($data);
 
             if (!empty($data[$field->Name])) {
-                if (in_array(EditableFileField::class, $field->getClassAncestry())) {
+                if (in_array(EditableFileField::class, $field->getClassAncestry() ?? [])) {
                     if (!empty($_FILES[$field->Name]['name'])) {
                         $foldername = $field->getFormField()->getFolderName();
 
@@ -371,15 +371,15 @@ public function process($data, $form)
                     $submittedFormField = $submittedFields->find('Name', $recipient->SendEmailFromField()->Name);
 
                     if ($submittedFormField && $submittedFormField->Value && is_string($submittedFormField->Value)) {
-                        $email->setReplyTo(explode(',', $submittedFormField->Value));
+                        $email->setReplyTo(explode(',', $submittedFormField->Value ?? ''));
                     }
                 } elseif ($recipient->EmailReplyTo) {
-                    $email->setReplyTo(explode(',', $recipient->EmailReplyTo));
+                    $email->setReplyTo(explode(',', $recipient->EmailReplyTo ?? ''));
                 }
 
                 // check for a specified from; otherwise fall back to server defaults
                 if ($recipient->EmailFrom) {
-                    $email->setFrom(explode(',', $recipient->EmailFrom));
+                    $email->setFrom(explode(',', $recipient->EmailFrom ?? ''));
                 }
 
                 // check to see if they are a dynamic reciever eg based on a dropdown field a user selected
@@ -390,12 +390,12 @@ public function process($data, $form)
                         $submittedFormField = $submittedFields->find('Name', $recipient->SendEmailToField()->Name);
 
                         if ($submittedFormField && is_string($submittedFormField->Value)) {
-                            $email->setTo(explode(',', $submittedFormField->Value));
+                            $email->setTo(explode(',', $submittedFormField->Value ?? ''));
                         } else {
-                            $email->setTo(explode(',', $recipient->EmailAddress));
+                            $email->setTo(explode(',', $recipient->EmailAddress ?? ''));
                         }
                     } else {
-                        $email->setTo(explode(',', $recipient->EmailAddress));
+                        $email->setTo(explode(',', $recipient->EmailAddress ?? ''));
                     }
                 } catch (Swift_RfcComplianceException $e) {
                     // The sending address is empty and/or invalid. Log and skip sending.
@@ -415,7 +415,7 @@ public function process($data, $form)
                 if ($emailSubject && $emailSubject->exists()) {
                     $submittedFormField = $submittedFields->find('Name', $recipient->SendEmailSubjectField()->Name);
 
-                    if ($submittedFormField && trim($submittedFormField->Value)) {
+                    if ($submittedFormField && trim($submittedFormField->Value ?? '')) {
                         $email->setSubject($submittedFormField->Value);
                     } else {
                         $email->setSubject(SSViewer::execute_string($recipient->EmailSubject, $mergeFields));
@@ -428,7 +428,7 @@ public function process($data, $form)
 
                 if ((bool)$recipient->SendPlain) {
                     // decode previously encoded html tags because the email is being sent as text/plain
-                    $body = html_entity_decode($emailData['Body']) . "\n";
+                    $body = html_entity_decode($emailData['Body'] ?? '') . "\n";
                     if (isset($emailData['Fields']) && !$emailData['HideFormData']) {
                         foreach ($emailData['Fields'] as $field) {
                             if ($field instanceof SubmittedFileField) {
@@ -474,7 +474,7 @@ public function process($data, $form)
                 // to allow us to get through the finshed method
                 if (!$this->Form()->getSecurityToken()->isEnabled()) {
                     $randNum = rand(1, 1000);
-                    $randHash = md5($randNum);
+                    $randHash = md5($randNum ?? '');
                     $session->set('FormProcessed', $randHash);
                     $session->set('FormProcessedNum', $randNum);
                 }
@@ -531,7 +531,7 @@ public function finished()
                 // make sure the session matches the SecurityID and is not left over from another form
                 if ($formProcessed != $securityID) {
                     // they may have disabled tokens on the form
-                    $securityID = md5($this->getRequest()->getSession()->get('FormProcessedNum'));
+                    $securityID = md5($this->getRequest()->getSession()->get('FormProcessedNum') ?? '');
                     if ($formProcessed != $securityID) {
                         return $this->redirect($this->Link() . $referrer);
                     }
@@ -571,7 +571,7 @@ protected function buildWatchJS($watch)
             $operations = implode(" {$conjunction} ", $rule['operations']);
             $target = $rule['targetFieldID'];
             $holder = $rule['holder'];
-            $isFormStep = strpos($target, 'EditableFormStep') !== false;
+            $isFormStep = strpos($target ?? '', 'EditableFormStep') !== false;
 
             $result .= <<<EOS
 \n
@@ -592,7 +592,7 @@ function (){
                 // This is particularly important beacause the next/prev page buttons logic is controlled by
                 // the visibility of the FormStep buttons
                 // The HTML for the FormStep buttons is defined in UserFormProgress.ss
-                $id = str_replace('#', '', $target);
+                $id = str_replace('#', '', $target ?? '');
                 $result .= <<<EOS
     $('.step-button-wrapper[data-for="{$id}"]').addClass('hide');
 EOS;
diff --git a/code/Extension/UpgradePolymorphicExtension.php b/code/Extension/UpgradePolymorphicExtension.php
index e8073a9e6..e40bd9a1b 100644
--- a/code/Extension/UpgradePolymorphicExtension.php
+++ b/code/Extension/UpgradePolymorphicExtension.php
@@ -67,7 +67,7 @@ public function requireDefaultRecords()
                     // If the defined data class doesn't have the UserForm trait applied, it's probably wrong. Re-map
                     // it to a default value that does
                     $classTraits = class_uses($relationshipObject);
-                    if (in_array(UserForm::class, $classTraits)) {
+                    if (in_array(UserForm::class, $classTraits ?? [])) {
                         continue;
                     }
 
diff --git a/code/Extension/UserFormValidator.php b/code/Extension/UserFormValidator.php
index 461734d89..ba3271010 100644
--- a/code/Extension/UserFormValidator.php
+++ b/code/Extension/UserFormValidator.php
@@ -29,7 +29,7 @@ public function php($data)
         foreach ($fields as $field) {
             if ($field instanceof EditableFormStep) {
                 // Page at top level, or after another page is ok
-                if (empty($stack) || (count($stack) === 1 && $stack[0] instanceof EditableFormStep)) {
+                if (empty($stack) || (count($stack ?? []) === 1 && $stack[0] instanceof EditableFormStep)) {
                     $stack = array($field);
                     $conditionalStep = $field->DisplayRules()->count() > 0;
                     continue;
diff --git a/code/Form/GridFieldAddClassesButton.php b/code/Form/GridFieldAddClassesButton.php
index 097b859f1..ae79a0c29 100644
--- a/code/Form/GridFieldAddClassesButton.php
+++ b/code/Form/GridFieldAddClassesButton.php
@@ -145,7 +145,7 @@ public function getClassesCreate($grid)
         }
 
         // Filter out classes without permission
-        return array_filter($classes, function ($class) {
+        return array_filter($classes ?? [], function ($class) {
             return singleton($class)->canCreate();
         });
     }
@@ -219,7 +219,7 @@ protected function getAction()
 
     public function handleAction(GridField $gridField, $actionName, $arguments, $data)
     {
-        switch (strtolower($actionName)) {
+        switch (strtolower($actionName ?? '')) {
             case $this->getAction():
                 return $this->handleAdd($gridField);
             default:
diff --git a/code/Form/UserFormsGridFieldFilterHeader.php b/code/Form/UserFormsGridFieldFilterHeader.php
index 752371b0f..44f3525bb 100644
--- a/code/Form/UserFormsGridFieldFilterHeader.php
+++ b/code/Form/UserFormsGridFieldFilterHeader.php
@@ -122,7 +122,7 @@ public function getHTMLFragments($gridField)
         $actions->addExtraClass('no-change-track');
 
         $colSpan = 2 + count($gridField->getConfig()->getComponentByType(GridFieldDataColumns::class)
-            ->getDisplayFields($gridField));
+            ->getDisplayFields($gridField) ?? []);
 
         $forTemplate = ArrayData::create(array(
             'Fields'    => $fields,
diff --git a/code/Form/UserFormsRequiredFields.php b/code/Form/UserFormsRequiredFields.php
index 70b13ff48..0d7c4b38f 100644
--- a/code/Form/UserFormsRequiredFields.php
+++ b/code/Form/UserFormsRequiredFields.php
@@ -113,11 +113,11 @@ private function validateRequired(FormField $field, array $data)
             if ($field instanceof FileField && isset($value['error']) && $value['error']) {
                 $error = true;
             } else {
-                $error = (count($value)) ? false : true;
+                $error = (count($value ?? [])) ? false : true;
             }
         } else {
             // assume a string or integer
-            $error = (strlen($value)) ? false : true;
+            $error = (strlen($value ?? '')) ? false : true;
         }
 
         return $error;
diff --git a/code/FormField/UserFormsCheckboxSetField.php b/code/FormField/UserFormsCheckboxSetField.php
index a3e268276..7d9092f2d 100644
--- a/code/FormField/UserFormsCheckboxSetField.php
+++ b/code/FormField/UserFormsCheckboxSetField.php
@@ -24,7 +24,7 @@ class UserFormsCheckboxSetField extends CheckboxSetField
      */
     public function getValidationAttributesHTML()
     {
-        $attrs = array_filter(array_keys($this->getAttributes()), function ($attr) {
+        $attrs = array_filter(array_keys($this->getAttributes() ?? []), function ($attr) {
             return !in_array($attr, ['data-rule-required', 'data-msg-required']);
         });
         return $this->getAttributesHTML(...$attrs);
@@ -60,8 +60,8 @@ public function validate($validator)
 
         $previous = $value = $this->Value();
 
-        if (is_string($value) && strstr($value, ",")) {
-            $value = explode(",", $value);
+        if (is_string($value) && strstr($value ?? '', ",")) {
+            $value = explode(",", $value ?? '');
         }
 
         // set the value as an array for parent validation
diff --git a/code/FormField/UserFormsFieldList.php b/code/FormField/UserFormsFieldList.php
index ae9948c01..a79398883 100644
--- a/code/FormField/UserFormsFieldList.php
+++ b/code/FormField/UserFormsFieldList.php
@@ -43,7 +43,7 @@ public function setParent(UserFormsFieldContainer $parent)
     public function clearEmptySteps()
     {
         foreach ($this as $field) {
-            if ($field instanceof UserFormsStepField && count($field->getChildren()) === 0) {
+            if ($field instanceof UserFormsStepField && count($field->getChildren() ?? []) === 0) {
                 $this->remove($field);
             }
         }
diff --git a/code/FormField/UserFormsOptionSetField.php b/code/FormField/UserFormsOptionSetField.php
index c71d107d5..8b66ada01 100644
--- a/code/FormField/UserFormsOptionSetField.php
+++ b/code/FormField/UserFormsOptionSetField.php
@@ -24,7 +24,7 @@ class UserFormsOptionSetField extends OptionsetField
      */
     public function getValidationAttributesHTML()
     {
-        $attrs = array_filter(array_keys($this->getAttributes()), function ($attr) {
+        $attrs = array_filter(array_keys($this->getAttributes() ?? []), function ($attr) {
             return !in_array($attr, ['data-rule-required', 'data-msg-required']);
         });
         return $this->getAttributesHTML(...$attrs);
diff --git a/code/Model/EditableCustomRule.php b/code/Model/EditableCustomRule.php
index 8349f5855..272bd562d 100644
--- a/code/Model/EditableCustomRule.php
+++ b/code/Model/EditableCustomRule.php
@@ -299,7 +299,7 @@ public function validateAgainstFormData(array $data)
      */
     public function toggleDisplayText($initialState, $invert = false)
     {
-        $action = strtolower($initialState) === 'hide' ? 'removeClass' : 'addClass';
+        $action = strtolower($initialState ?? '') === 'hide' ? 'removeClass' : 'addClass';
         if ($invert) {
             $action = $action === 'removeClass' ? 'addClass' : 'removeClass';
         }
@@ -316,7 +316,7 @@ public function toggleDisplayText($initialState, $invert = false)
      */
     public function toggleDisplayEvent($initialState, $invert = false)
     {
-        $action = strtolower($initialState) === 'hide' ? 'show' : 'hide';
+        $action = strtolower($initialState ?? '') === 'hide' ? 'show' : 'hide';
         if ($invert) {
             $action = $action === 'hide' ? 'show' : 'hide';
         }
diff --git a/code/Model/EditableFormField.php b/code/Model/EditableFormField.php
index 41e349623..d01de75fe 100755
--- a/code/Model/EditableFormField.php
+++ b/code/Model/EditableFormField.php
@@ -358,7 +358,7 @@ public function requireDefaultRecords()
      */
     protected function getDisplayRuleFields()
     {
-        $allowedClasses = array_keys($this->getEditableFieldClasses(false));
+        $allowedClasses = array_keys($this->getEditableFieldClasses(false) ?? []);
         $editableColumns = new GridFieldEditableColumns();
         $editableColumns->setDisplayFields([
             'ConditionFieldID' => function ($record, $column, $grid) use ($allowedClasses) {
@@ -584,7 +584,7 @@ public function isNew()
             return false;
         }
 
-        return stripos($this->ID, 'new') === 0;
+        return stripos($this->ID ?? '', 'new') === 0;
     }
 
     /**
@@ -612,7 +612,7 @@ public function getIcon()
         $shortClass = end($classNamespaces);
 
         $resource = ModuleLoader::getModule('silverstripe/userforms')
-            ->getResource('images/' . strtolower($shortClass) . '.png');
+            ->getResource('images/' . strtolower($shortClass ?? '') . '.png');
 
         if (!$resource->exists()) {
             return '';
@@ -782,7 +782,7 @@ protected function updateFormField($field)
         }
 
         // if this field has a placeholder
-        if (strlen($this->Placeholder) >= 0) {
+        if (strlen($this->Placeholder ?? '') >= 0) {
             $field->setAttribute('placeholder', $this->Placeholder);
         }
     }
@@ -983,10 +983,10 @@ public function formatDisplayRules()
             $fieldToWatch = $formFieldWatch->getSelectorFieldOnly();
 
             $expression = $rule->buildExpression();
-            if (!in_array($fieldToWatch, $result['selectors'])) {
+            if (!in_array($fieldToWatch, $result['selectors'] ?? [])) {
                 $result['selectors'][] = $fieldToWatch;
             }
-            if (!in_array($expression['event'], $result['events'])) {
+            if (!in_array($expression['event'], $result['events'] ?? [])) {
                 $result['events'][] = $expression['event'];
             }
             $result['operations'][] = $expression['operation'];
@@ -999,7 +999,7 @@ public function formatDisplayRules()
             $result['holder_event_opposite'] = $rule->toggleDisplayEvent($result['initialState'], true);
         }
 
-        return (count($result['selectors'])) ? $result : null;
+        return (count($result['selectors'] ?? [])) ? $result : null;
     }
 
     /**
@@ -1050,7 +1050,7 @@ public function isDisplayed(array $data)
      */
     public function DisplayRulesConjunctionNice()
     {
-        return (strtolower($this->DisplayRulesConjunction) === 'or') ? '||' : '&&';
+        return (strtolower($this->DisplayRulesConjunction ?? '') === 'or') ? '||' : '&&';
     }
 
     /**
diff --git a/code/Model/EditableFormField/EditableFileField.php b/code/Model/EditableFormField/EditableFileField.php
index 277bde53a..2c8b625f3 100755
--- a/code/Model/EditableFormField/EditableFileField.php
+++ b/code/Model/EditableFormField/EditableFileField.php
@@ -209,7 +209,7 @@ public function getFormField()
         $field->getValidator()->setAllowedExtensions(
             array_diff(
                 // filter out '' since this would be a regex problem on JS end
-                array_filter(Config::inst()->get(File::class, 'allowed_extensions')),
+                array_filter(Config::inst()->get(File::class, 'allowed_extensions') ?? []),
                 $this->config()->get('allowed_extensions_blacklist')
             )
         );
@@ -223,7 +223,7 @@ public function getFormField()
         $folder = $this->Folder();
         if ($folder && $folder->exists()) {
             $field->setFolderName(
-                preg_replace("/^assets\//", "", $folder->Filename)
+                preg_replace("/^assets\//", "", $folder->Filename ?? '')
             );
         }
 
diff --git a/code/Model/Recipient/EmailRecipient.php b/code/Model/Recipient/EmailRecipient.php
index a132617eb..11af738e8 100644
--- a/code/Model/Recipient/EmailRecipient.php
+++ b/code/Model/Recipient/EmailRecipient.php
@@ -143,9 +143,9 @@ public function onBeforeWrite()
 
         // email addresses have trim() applied to them during validation for a slightly nicer UX
         // apply trim() here too before saving to the database
-        $this->EmailAddress = trim($this->EmailAddress);
-        $this->EmailFrom = trim($this->EmailFrom);
-        $this->EmailReplyTo = trim($this->EmailReplyTo);
+        $this->EmailAddress = trim($this->EmailAddress ?? '');
+        $this->EmailFrom = trim($this->EmailFrom ?? '');
+        $this->EmailReplyTo = trim($this->EmailReplyTo ?? '');
     }
 
     public function summaryFields()
@@ -272,9 +272,9 @@ public function getCMSFields()
             // an AJAX request, e.g. saving a GridFieldDetailForm
             $remove = ['/edit', '/ItemEditForm'];
             foreach ($remove as $badSuffix) {
-                $badSuffixLength = strlen($badSuffix);
-                if (substr($currentUrl, -$badSuffixLength) === $badSuffix) {
-                    $currentUrl = substr($currentUrl, 0, -$badSuffixLength);
+                $badSuffixLength = strlen($badSuffix ?? '');
+                if (substr($currentUrl ?? '', -$badSuffixLength) === $badSuffix) {
+                    $currentUrl = substr($currentUrl ?? '', 0, -$badSuffixLength);
                 }
             }
             $previewUrl = Controller::join_links($currentUrl, 'preview');
@@ -534,7 +534,7 @@ public function getEmailTemplateDropdownValues()
         $found = $finder->find(BASE_PATH . DIRECTORY_SEPARATOR . $templateDirectory);
 
         foreach ($found as $key => $value) {
-            $template = pathinfo($value);
+            $template = pathinfo($value ?? '');
             $absoluteFilename = $template['dirname'] . DIRECTORY_SEPARATOR . $template['filename'];
 
             // Optionally remove vendor/ path prefixes
@@ -544,10 +544,10 @@ public function getEmailTemplateDropdownValues()
             } else {
                 $prefixToStrip = BASE_PATH;
             }
-            $templatePath = substr($absoluteFilename, strlen($prefixToStrip) + 1);
+            $templatePath = substr($absoluteFilename ?? '', strlen($prefixToStrip ?? '') + 1);
 
             // Optionally remove "templates/" ("templates\" on Windows respectively) prefixes
-            if (preg_match('#(?<=templates' . preg_quote(DIRECTORY_SEPARATOR, '#') . ').*$#', $templatePath, $matches)) {
+            if (preg_match('#(?<=templates' . preg_quote(DIRECTORY_SEPARATOR, '#') . ').*$#', $templatePath ?? '', $matches)) {
                 $templatePath = $matches[0];
             }
 
@@ -573,9 +573,9 @@ public function validate()
         foreach ($checkEmail as $check => $translation) {
             if ($this->$check) {
                 //may be a comma separated list of emails
-                $addresses = explode(',', $this->$check);
+                $addresses = explode(',', $this->$check ?? '');
                 foreach ($addresses as $address) {
-                    $trimAddress = trim($address);
+                    $trimAddress = trim($address ?? '');
                     if ($trimAddress && !Email::is_valid_address($trimAddress)) {
                         $error = _t(
                             __CLASS__.".$translation",
diff --git a/code/Modifier/UnderscoreSegmentFieldModifier.php b/code/Modifier/UnderscoreSegmentFieldModifier.php
index f100b6d28..d50ea3100 100644
--- a/code/Modifier/UnderscoreSegmentFieldModifier.php
+++ b/code/Modifier/UnderscoreSegmentFieldModifier.php
@@ -8,11 +8,11 @@ class UnderscoreSegmentFieldModifier extends SlugSegmentFieldModifier
 {
     public function getPreview($value)
     {
-        return str_replace('-', '_', parent::getPreview($value));
+        return str_replace('-', '_', parent::getPreview($value) ?? '');
     }
 
     public function getSuggestion($value)
     {
-        return str_replace('-', '_', parent::getSuggestion($value));
+        return str_replace('-', '_', parent::getSuggestion($value) ?? '');
     }
 }
diff --git a/code/Task/UserFormsColumnCleanTask.php b/code/Task/UserFormsColumnCleanTask.php
index 2ec8a5218..b20731410 100644
--- a/code/Task/UserFormsColumnCleanTask.php
+++ b/code/Task/UserFormsColumnCleanTask.php
@@ -57,7 +57,7 @@ public function run($request)
                     DB::query($query);
                     $backedUp = 1;
                 }
-                if (!isset($columns[$column]) && !in_array($column, $this->keepColumns)) {
+                if (!isset($columns[$column]) && !in_array($column, $this->keepColumns ?? [])) {
                     echo "Dropping $column from $db <br />";
                     $query = "ALTER TABLE $db DROP COLUMN $column";
                     DB::query($query);
diff --git a/code/UserForm.php b/code/UserForm.php
index e3632776f..2909959c8 100644
--- a/code/UserForm.php
+++ b/code/UserForm.php
@@ -255,7 +255,7 @@ public function getCMSFields()
             $columns = array();
 
             foreach (DB::query($columnSQL)->map() as $name => $title) {
-                $columns[$name] = trim(strtr($title, '.', ' '));
+                $columns[$name] = trim(strtr($title ?? '', '.', ' '));
             }
 
             $config = GridFieldConfig::create();
diff --git a/tests/php/Control/UserDefinedFormAdminTest.php b/tests/php/Control/UserDefinedFormAdminTest.php
index 1effe7520..80dadf7f2 100644
--- a/tests/php/Control/UserDefinedFormAdminTest.php
+++ b/tests/php/Control/UserDefinedFormAdminTest.php
@@ -106,7 +106,7 @@ public function testConfirmfolderformFields()
             null,
             ['X-FormSchema-Request' => 'auto,schema,state,errors']
         );
-        $schemaData = json_decode($response->getBody(), true);
+        $schemaData = json_decode($response->getBody() ?? '', true);
 
         $this->assertEquals('ConfirmFolderForm', $schemaData['schema']['name']);
         $this->assertField($schemaData, 'FolderOptions', ['component' => 'OptionsetField']);
@@ -128,7 +128,7 @@ public function testConfirmfolderformDefaultFolder()
             null,
             ['X-FormSchema-Request' => 'auto,schema,state,errors']
         );
-        $schemaData = json_decode($response->getBody(), true);
+        $schemaData = json_decode($response->getBody() ?? '', true);
 
         $this->assertEquals('ConfirmFolderForm', $schemaData['schema']['name']);
         $this->assertField($schemaData, 'FolderOptions', ['component' => 'OptionsetField']);
diff --git a/tests/php/Control/UserDefinedFormControllerTest.php b/tests/php/Control/UserDefinedFormControllerTest.php
index a198f4134..f0acfbe0d 100644
--- a/tests/php/Control/UserDefinedFormControllerTest.php
+++ b/tests/php/Control/UserDefinedFormControllerTest.php
@@ -96,7 +96,7 @@ public function testProcess()
 
         // submitted html tags are escaped for the html value
         $value = 'class="readonly">My body html Basic Value &lt;b&gt;HTML&lt;/b&gt;</span>';
-        $this->assertTrue(strpos($email['Content'], $value) !== false, 'Email contains the merge field value');
+        $this->assertTrue(strpos($email['Content'] ?? '', $value ?? '') !== false, 'Email contains the merge field value');
 
         $value = $parser->getBySelector('dd');
         $this->assertEquals('Basic Value <b>HTML</b>', (string) $value[0], 'Email contains the value');
@@ -198,14 +198,14 @@ public function testForm()
         $this->assertEquals($controller->Form()->getName(), 'Form_' . $form->ID, 'The form is referenced as Form');
         $this->assertEquals($controller->Form()->Fields()->Count(), 1); // disabled SecurityID token fields
         $this->assertEquals($controller->Form()->Actions()->Count(), 1);
-        $this->assertEquals(count($controller->Form()->getValidator()->getRequired()), 0);
+        $this->assertEquals(count($controller->Form()->getValidator()->getRequired() ?? []), 0);
 
         $requiredForm = $this->objFromFixture(UserDefinedForm::class, 'validation-form');
         $controller = new UserDefinedFormController($requiredForm);
 
         $this->assertEquals($controller->Form()->Fields()->Count(), 1); // disabled SecurityID token fields
         $this->assertEquals($controller->Form()->Actions()->Count(), 1);
-        $this->assertEquals(count($controller->Form()->getValidator()->getRequired()), 1);
+        $this->assertEquals(count($controller->Form()->getValidator()->getRequired() ?? []), 1);
     }
 
     public function testGetFormFields()
@@ -413,7 +413,7 @@ public function testImageThumbnailCreated()
                 'type' => 'image/jpeg',
                 'tmp_name' => $path,
                 'error' => 0,
-                'size' => filesize($path),
+                'size' => filesize($path ?? ''),
             ]
         ];
         $_FILES[$field->Name] = $data[$field->Name];
@@ -449,7 +449,7 @@ public function testRecipientAttachment()
                 'type' => 'image/jpeg',
                 'tmp_name' => $path,
                 'error' => 0,
-                'size' => filesize($path),
+                'size' => filesize($path ?? ''),
             ]
         ];
         $_FILES[$field->Name] = $data[$field->Name];
diff --git a/tests/php/FormField/UserFormsCheckboxSetFieldTest.php b/tests/php/FormField/UserFormsCheckboxSetFieldTest.php
index be36f0064..85738e677 100644
--- a/tests/php/FormField/UserFormsCheckboxSetFieldTest.php
+++ b/tests/php/FormField/UserFormsCheckboxSetFieldTest.php
@@ -46,6 +46,6 @@ public function testCustomErrorMessageValidationAttributesHTML()
         $userFormsCheckboxSetField = $editableCheckboxGroupField->getFormField();
         $html = $userFormsCheckboxSetField->renderWith(UserFormsCheckboxSetField::class)->getValue();
         $attributesHTML = 'data-rule-required="true" data-msg-required="My custom error message with &amp;#039;single&amp;#039; and &amp;quot;double&amp;quot; quotes"';
-        $this->assertTrue(strpos($html, $attributesHTML) > 0);
+        $this->assertTrue(strpos($html ?? '', $attributesHTML ?? '') > 0);
     }
 }
diff --git a/tests/php/FormField/UserFormsOptionSetFieldTest.php b/tests/php/FormField/UserFormsOptionSetFieldTest.php
index abd27164a..9d7096140 100644
--- a/tests/php/FormField/UserFormsOptionSetFieldTest.php
+++ b/tests/php/FormField/UserFormsOptionSetFieldTest.php
@@ -19,6 +19,6 @@ public function testCustomErrorMessageValidationAttributesHTML()
         $userFormsOptionSetField = $radio->getFormField();
         $html = $userFormsOptionSetField->renderWith(UserFormsOptionSetField::class)->getValue();
         $attributesHTML = 'data-rule-required="true" data-msg-required="My custom error message with &amp;#039;single&amp;#039; and &amp;quot;double&amp;quot; quotes"';
-        $this->assertTrue(strpos($html, $attributesHTML) > 0);
+        $this->assertTrue(strpos($html ?? '', $attributesHTML ?? '') > 0);
     }
 }
diff --git a/tests/php/Model/UserDefinedFormTest.php b/tests/php/Model/UserDefinedFormTest.php
index 6f040f487..d78c1a1b1 100644
--- a/tests/php/Model/UserDefinedFormTest.php
+++ b/tests/php/Model/UserDefinedFormTest.php
@@ -100,8 +100,8 @@ public function testGetCMSFieldsShowInSummary()
 
         $summaryFields = $gridFieldDataColumns->getDisplayFields($submissionsgrid);
 
-        $this->assertContains('SummaryShow', array_keys($summaryFields), 'Summary field not showing displayed field');
-        $this->assertNotContains('SummaryHide', array_keys($summaryFields), 'Summary field showing displayed field');
+        $this->assertContains('SummaryShow', array_keys($summaryFields ?? []), 'Summary field not showing displayed field');
+        $this->assertNotContains('SummaryHide', array_keys($summaryFields ?? []), 'Summary field showing displayed field');
     }
 
     public function testEmailRecipientPopup()
@@ -177,13 +177,13 @@ public function testGetEmailTemplateDropdownValues()
 
         // Installation path can be as a project when testing in Travis, so check partial match
         $foundKey = false;
-        foreach (array_keys($result) as $key) {
-            if (strpos($key, 'email' . DIRECTORY_SEPARATOR . 'SubmittedFormEmail') !== false) {
+        foreach (array_keys($result ?? []) as $key) {
+            if (strpos($key ?? '', 'email' . DIRECTORY_SEPARATOR . 'SubmittedFormEmail') !== false) {
                 $foundKey = true;
             }
         }
         $this->assertTrue($foundKey);
-        $this->assertTrue(in_array('SubmittedFormEmail', array_values($result)));
+        $this->assertTrue(in_array('SubmittedFormEmail', array_values($result ?? [])));
     }
 
     public function testEmailTemplateExists()
@@ -195,7 +195,7 @@ public function testEmailTemplateExists()
         $recipient->EmailAddress = 'test@example.com';
 
         // Set the default template
-        $recipient->EmailTemplate = current(array_keys($recipient->getEmailTemplateDropdownValues()));
+        $recipient->EmailTemplate = current(array_keys($recipient->getEmailTemplateDropdownValues() ?? []));
         $recipient->write();
 
         // The default template exists