diff --git a/UPGRADE.md b/UPGRADE.md
index 037b3b74245..a4c38585761 100644
--- a/UPGRADE.md
+++ b/UPGRADE.md
@@ -1,5 +1,10 @@
 # Upgrade to 3.0
 
+## BC BREAK: Removed support for DB-generated UUIDs
+
+The support for DB-generated UUIDs was removed as non-portable.
+Please generate UUIDs on the application side (e.g. using [ramsey/uuid](https://packagist.org/packages/ramsey/uuid)).
+
 ## BC BREAK: Removed MsSQLKeywords class
 
 The `Doctrine\DBAL\Platforms\MsSQLKeywords` has been removed.
diff --git a/lib/Doctrine/DBAL/Platforms/AbstractPlatform.php b/lib/Doctrine/DBAL/Platforms/AbstractPlatform.php
index 9a89a4b4d44..4c2a7cae325 100644
--- a/lib/Doctrine/DBAL/Platforms/AbstractPlatform.php
+++ b/lib/Doctrine/DBAL/Platforms/AbstractPlatform.php
@@ -616,20 +616,6 @@ public function getRegexpExpression()
         throw DBALException::notSupported(__METHOD__);
     }
 
-    /**
-     * Returns the global unique identifier expression.
-     *
-     * @deprecated Use application-generated UUIDs instead
-     *
-     * @return string
-     *
-     * @throws DBALException If not supported on this platform.
-     */
-    public function getGuidExpression()
-    {
-        throw DBALException::notSupported(__METHOD__);
-    }
-
     /**
      * Returns the SQL snippet to get the average value of a column.
      *
diff --git a/lib/Doctrine/DBAL/Platforms/MySqlPlatform.php b/lib/Doctrine/DBAL/Platforms/MySqlPlatform.php
index 17b7df98bd4..783c94af1c2 100644
--- a/lib/Doctrine/DBAL/Platforms/MySqlPlatform.php
+++ b/lib/Doctrine/DBAL/Platforms/MySqlPlatform.php
@@ -78,16 +78,6 @@ public function getRegexpExpression()
         return 'RLIKE';
     }
 
-    /**
-     * {@inheritDoc}
-     *
-     * @deprecated Use application-generated UUIDs instead
-     */
-    public function getGuidExpression()
-    {
-        return 'UUID()';
-    }
-
     /**
      * {@inheritDoc}
      */
diff --git a/lib/Doctrine/DBAL/Platforms/OraclePlatform.php b/lib/Doctrine/DBAL/Platforms/OraclePlatform.php
index 5d5d4c49424..f0f14012a5a 100644
--- a/lib/Doctrine/DBAL/Platforms/OraclePlatform.php
+++ b/lib/Doctrine/DBAL/Platforms/OraclePlatform.php
@@ -84,16 +84,6 @@ public function getLocateExpression($str, $substr, $startPos = false)
         return 'INSTR(' . $str . ', ' . $substr . ', ' . $startPos . ')';
     }
 
-    /**
-     * {@inheritDoc}
-     *
-     * @deprecated Use application-generated UUIDs instead
-     */
-    public function getGuidExpression()
-    {
-        return 'SYS_GUID()';
-    }
-
     /**
      * {@inheritdoc}
      */
diff --git a/lib/Doctrine/DBAL/Platforms/PostgreSqlPlatform.php b/lib/Doctrine/DBAL/Platforms/PostgreSqlPlatform.php
index b908e9f6bf9..c9389a7aa7a 100644
--- a/lib/Doctrine/DBAL/Platforms/PostgreSqlPlatform.php
+++ b/lib/Doctrine/DBAL/Platforms/PostgreSqlPlatform.php
@@ -1015,16 +1015,6 @@ public function getTimeTypeDeclarationSQL(array $fieldDeclaration)
         return 'TIME(0) WITHOUT TIME ZONE';
     }
 
-    /**
-     * {@inheritDoc}
-     *
-     * @deprecated Use application-generated UUIDs instead
-     */
-    public function getGuidExpression()
-    {
-        return 'UUID_GENERATE_V4()';
-    }
-
     /**
      * {@inheritDoc}
      */
diff --git a/lib/Doctrine/DBAL/Platforms/SQLAnywherePlatform.php b/lib/Doctrine/DBAL/Platforms/SQLAnywherePlatform.php
index 6a3058dc9dc..745c2bb95cb 100644
--- a/lib/Doctrine/DBAL/Platforms/SQLAnywherePlatform.php
+++ b/lib/Doctrine/DBAL/Platforms/SQLAnywherePlatform.php
@@ -662,16 +662,6 @@ public function getForUpdateSQL()
         return '';
     }
 
-    /**
-     * {@inheritdoc}
-     *
-     * @deprecated Use application-generated UUIDs instead
-     */
-    public function getGuidExpression()
-    {
-        return 'NEWID()';
-    }
-
     /**
      * {@inheritdoc}
      */
diff --git a/lib/Doctrine/DBAL/Platforms/SQLServerPlatform.php b/lib/Doctrine/DBAL/Platforms/SQLServerPlatform.php
index 71dbf90c095..0fe05c9a882 100644
--- a/lib/Doctrine/DBAL/Platforms/SQLServerPlatform.php
+++ b/lib/Doctrine/DBAL/Platforms/SQLServerPlatform.php
@@ -1000,16 +1000,6 @@ public function getDropViewSQL($name)
         return 'DROP VIEW ' . $name;
     }
 
-    /**
-     * {@inheritDoc}
-     *
-     * @deprecated Use application-generated UUIDs instead
-     */
-    public function getGuidExpression()
-    {
-        return 'NEWID()';
-    }
-
     /**
      * {@inheritDoc}
      */
diff --git a/lib/Doctrine/DBAL/Platforms/SqlitePlatform.php b/lib/Doctrine/DBAL/Platforms/SqlitePlatform.php
index 70481d524aa..ccb9284fa79 100644
--- a/lib/Doctrine/DBAL/Platforms/SqlitePlatform.php
+++ b/lib/Doctrine/DBAL/Platforms/SqlitePlatform.php
@@ -40,19 +40,6 @@ public function getRegexpExpression()
         return 'REGEXP';
     }
 
-    /**
-     * {@inheritDoc}
-     *
-     * @deprecated Use application-generated UUIDs instead
-     */
-    public function getGuidExpression()
-    {
-        return "HEX(RANDOMBLOB(4)) || '-' || HEX(RANDOMBLOB(2)) || '-4' || "
-            . "SUBSTR(HEX(RANDOMBLOB(2)), 2) || '-' || "
-            . "SUBSTR('89AB', 1 + (ABS(RANDOM()) % 4), 1) || "
-            . "SUBSTR(HEX(RANDOMBLOB(2)), 2) || '-' || HEX(RANDOMBLOB(6))";
-    }
-
     /**
      * {@inheritDoc}
      */
diff --git a/tests/Doctrine/Tests/DBAL/Functional/Ticket/DBAL421Test.php b/tests/Doctrine/Tests/DBAL/Functional/Ticket/DBAL421Test.php
deleted file mode 100644
index af41670690a..00000000000
--- a/tests/Doctrine/Tests/DBAL/Functional/Ticket/DBAL421Test.php
+++ /dev/null
@@ -1,56 +0,0 @@
-<?php
-
-namespace Doctrine\Tests\DBAL\Functional\Ticket;
-
-use Doctrine\Tests\DbalFunctionalTestCase;
-use function in_array;
-use function preg_match;
-
-/**
- * @group DBAL-421
- */
-class DBAL421Test extends DbalFunctionalTestCase
-{
-    protected function setUp()
-    {
-        parent::setUp();
-
-        $platform = $this->connection->getDatabasePlatform()->getName();
-        if (in_array($platform, ['mysql', 'sqlite'])) {
-            return;
-        }
-
-        $this->markTestSkipped('Currently restricted to MySQL and SQLite.');
-    }
-
-    public function testGuidShouldMatchPattern()
-    {
-        $guid    = $this->connection->query($this->getSelectGuidSql())->fetchColumn();
-        $pattern = '/[0-9A-F]{8}\-[0-9A-F]{4}\-[0-9A-F]{4}\-[8-9A-B][0-9A-F]{3}\-[0-9A-F]{12}/i';
-        self::assertEquals(1, preg_match($pattern, $guid), 'GUID does not match pattern');
-    }
-
-    /**
-     * This test does (of course) not proof that all generated GUIDs are
-     * random, it should however provide some basic confidence.
-     */
-    public function testGuidShouldBeRandom()
-    {
-        $statement = $this->connection->prepare($this->getSelectGuidSql());
-        $guids     = [];
-
-        for ($i = 0; $i < 99; $i++) {
-            $statement->execute();
-            $guid = $statement->fetchColumn();
-            self::assertNotContains($guid, $guids, 'Duplicate GUID detected');
-            $guids[] = $guid;
-        }
-
-        $statement->closeCursor();
-    }
-
-    private function getSelectGuidSql()
-    {
-        return 'SELECT ' . $this->connection->getDatabasePlatform()->getGuidExpression();
-    }
-}
diff --git a/tests/Doctrine/Tests/DBAL/Platforms/SQLAnywherePlatformTest.php b/tests/Doctrine/Tests/DBAL/Platforms/SQLAnywherePlatformTest.php
index a37b6f37033..86a3d9b3919 100644
--- a/tests/Doctrine/Tests/DBAL/Platforms/SQLAnywherePlatformTest.php
+++ b/tests/Doctrine/Tests/DBAL/Platforms/SQLAnywherePlatformTest.php
@@ -635,7 +635,6 @@ public function testGeneratesSQLSnippets()
         self::assertEquals('Y-m-d H:i:s.u', $this->platform->getDateTimeFormatString());
         self::assertEquals('H:i:s.u', $this->platform->getTimeFormatString());
         self::assertEquals('', $this->platform->getForUpdateSQL());
-        self::assertEquals('NEWID()', $this->platform->getGuidExpression());
         self::assertEquals('LOCATE(string_column, substring_column)', $this->platform->getLocateExpression('string_column', 'substring_column'));
         self::assertEquals('LOCATE(string_column, substring_column, 1)', $this->platform->getLocateExpression('string_column', 'substring_column', 1));
         self::assertEquals("HASH(column, 'MD5')", $this->platform->getMd5Expression('column'));