[5.10]: Pasted Matrix blocks not visually rendered until page refresh

[frontedbe]

What happened?

Description

When pasting Matrix blocks (via the field-level "Paste" action), the paste operation appears to succeed — the entry's modified indicator (blue left border) appears, confirming a change was registered — but the pasted blocks are not visually rendered in the field. After a page refresh, the pasted blocks appear correctly in the expected position.

This suggests the paste action writes the data to the draft state but fails to trigger the necessary DOM update to render the newly inserted blocks in the UI.

Screencast demonstrating the issue: screencast

Steps to reproduce

1. Open an entry with a Matrix field containing one or more blocks.
2. Copy one or more Matrix blocks.
3. Use the "Paste" action on the Matrix field to paste the copied blocks.
4. Observe the result.

Expected behavior

The pasted blocks should immediately appear in the Matrix field without requiring a page refresh.

Actual behavior

The paste action completes silently — the entry's modified indicator (blue left border) appears, confirming the data was changed — but the pasted blocks are not rendered in the UI. Refreshing the page reveals the blocks in the correct position.

Craft CMS version

5.10.1

Craft CMS version

5.10.1

PHP version

8.3.30

Operating system and version

macOS 26.3

Database type and version

MySQL 8.0.40

Image driver and version

Imagick 3.8.1 (ImageMagick 7.1.1-43)

Installed plugins and versions

• Bugsnag 5.0.2
• Child Me! 2.2.3
• CKEditor 5.6.1
• Craft MCP v1.2.2
• Dumper 5.0.1
• Formie 3.1.25
• Google Maps 5.2.2
• Hyper 2.3.7
• Image toolbox 3.0.1
• Matrix Field Preview 5.6.1
• Navigation 3.0.22
• SEO 5.1.21
• Sprig 3.7.2
• Vite 5.0.1

[linear-code]

CMS-2105

[brandonkelly]

This is working on my end.

Are you getting any JavaScript errors on the page?

[frontedbe]

Uncaught (in promise) TypeError: Cannot read properties of undefined (reading 'createDocumentFragment')
    at De (jquery.js?v=1779174281:2:35893)
    at _e (jquery.js?v=1779174281:2:45754)
    at T.fn.init.before (jquery.js?v=1779174281:2:47756)
    at T.each.T.fn.<computed> [as insertBefore] (jquery.js?v=1779174281:2:48988)
    at MatrixInput.js:266:25
    at f (MatrixInput.js:2:1)
    at Generator.<anonymous> (MatrixInput.js:2:1)
    at Generator.next (MatrixInput.js:2:1)
    at i (MatrixInput.js:2:1)
    at o (MatrixInput.js:2:1)

screenshot

[brandonkelly]

Certainly seems related!

Any chance you can send your database backup and Composer files into support@craftcms.com? We can try to reproduce with your site from there.

[superflausch]

We’re seeing the same issue across several of our projects. It most likely was introduced with the 5.10.x releases, though I still need to confirm that properly.

One important detail is that this does not seem to affect all Matrix fields. I’m not yet sure what the deciding factor is.

Happy to provide database dumps or Composer files if that would help narrow it down.

[frontedbe]

@superflausch I've already sent my composer files and db to the support team and they could replicate the bug, so sit tight :) they also told me this:

Oh and to add, if this is blocking any work, it seems to only be with the View Mode set to blocks. If you change that to any of the others, the paste should work.

[brandonkelly]

Craft 5.10.2 is out now with a fix for this. Thanks all!

[frontedbe]

Great, thanks! One small thing that I noticed: when I paste the blocks, and try to collaps them, they don't collapse, I need to save it first.