[4.x]: Validation of assets on upload no longer works as expected

[aelvan]

What happened?

Description

Adding validation errors to assets on upload no longer works as expected (ie the way it used to do in Craft 3.x).

Steps to reproduce

1. Add the following event handler to a module or a plugin:

Event::on(
    Asset::class,
    Model::EVENT_BEFORE_VALIDATE,
    static function (ModelEvent $event) {
        /** @var Asset $asset */
        $asset = $event->sender;
        $asset->addError('title', 'This asset does not validate!');
    }
);

2. Upload an asset

Expected behavior

In Craft 3.x, this resulted in an alert popping up saying "Upload failed. The error message was: “This asset does not validate!”", and when clicking "Ok" the upload was aborted and you returned to the assets element index.

Actual behavior

In Craft 4.x, there is no error message, the status bar just stays on screen and nothing happens.

Two things I noticed:

• In Craft 3, the response is a http 200, while in Craft 4 it's a 400
• In Craft 3, a json object with one key, error, is returned, while in Craft 4 the key is called message.

Craft CMS version

4.0.1

PHP version

8.1.5

Operating system and version

macOS 11.2

Database type and version

MySQL 5.7.38

Image driver and version

Imagick 3.7.0 (ImageMagick 7.1.0-32)

Installed plugins and versions

[timkelty]

@aelvan Thanks for the report! Returning a 400 with message is correct in Craft 4, it just wasn't being handled properly.

This is fixed on #11177 if you want to test with dev-fix-asset-upload as 4.0.2.

[brandonkelly]

That fix is merged into develop and release/4.0.2 now.

[brandonkelly]

Craft 4.0.2 is out now with the fix for this.