[4.x]: Applying YAML changes from Project Config utility hangs indefinitely (loader never finishes)

[ks-brijeshr]

What happened?

Description

When applying project config YAML changes via Utilities → Project Config → Apply YAML Changes → "Apply changes only", the page shows a loading spinner indefinitely and the changes are never applied. I left it running for 25–30 minutes and the loader keeps spinning without completing, erroring, or applying any of the pending changes.

Steps to reproduce

1. Have pending project config YAML changes (shown in the diff on the Project Config utility page).
2. Go to Utilities → Project Config.
3. Click "Apply changes only".
4. The page navigates to a blank screen showing only a loading spinner, indefinitely (~25–30 min, never completes).

Expected behavior

Clicking "Apply changes only" should apply the pending YAML changes and return to the control panel, or throw a clear error if something fails.

Actual behavior

The page navigates to a blank screen showing only the loading spinner. Changes are never applied, no error is shown, and the request hangs for an unbounded amount of time. The pending changes preview renders fine; only the apply step hangs.

Craft CMS version

4.17.8

PHP version

8.0.30

Operating system and version

No response

Database type and version

No response

Image driver and version

No response

Installed plugins and versions

Loder shows after clcik on the apply changes only button:-

[linear-code]

CMS-2194

[brandonkelly]

I can’t reproduce that on my end. Can you send your database backup, Composer files, and the incoming config/project/ folder over to support@craftcms.com? If you have any custom plugins/modules, please send those as well.