Editing an asset throws "An unknown error occurred."

[tomastech]

Description

I have few images in jpg and png format. They are sitting under local folder @web/assets @webroot/assets.

When I go into Assets > [select image] > Edit Asset and try to update filename or title, following error flashes at the top "An unknown error occurred." Just clicking save button without any changes triggers this error.

Looking at my devtools console reports the following:

POST https://example.test/index.php?p=admin/actions/elements/save-element 500 ()

// Form Data
includeTableAttributesForSource: folder:1
siteId: 1
elementId: 66
namespace: editor_XtQItnkq3Y
elementId: 66
siteId: 1
editor_XtQItnkq3Y[newFilename]: sample-image-01.png
editor_XtQItnkq3Y[title]: Sample Image 01
editor_XtQItnkq3Y[fieldLayoutId]: 3

// Response
{"error":"Argument 1 passed to craft\\helpers\\Assets::getFileKindByExtension() must be of the type string, null given, called in /home/vagrant/sites/example/vendor/craftcms/cms/src/elements/Asset.php on line 1215"}

My setup has two "sites" (multi-language), default site being in English and another in French.

Steps to reproduce

1. Navigate to /admin/assets
2. Choose existing volume and select an image
3. Click on action cog and choose "Edit asset"
4. Click "Save"
5. Notice "An unknown error occurred." error is shown

Additional info

• Craft version: 3.0.3
• PHP version: 7.2.3
• Database driver & version: MySQL 5.7.21
• Plugins & versions:
  • Imager v2.0.0
  • Mailchimp Subscribe 2.0.0
  • Minify 1.2.8
  • Redactor 1.1.0
  • SEO 3.2.4
  • SimpleMap 3.3.3
  • Typed link field 1.0.7

[ostark]

Fixed here #2764
Update to 3.0.3.1