SFPx web parts cannot be edited on classic pages on SharePoint Server 2019 after July 2025 updates

[corriespondent]

Target SharePoint environment

SharePoint Server 2019 (on-premise)

What SharePoint development model, framework, SDK or API is this about?

💥 SharePoint Framework

Developer environment

Windows

What browser(s) / client(s) have you tested

• 💥 Internet Explorer
• 💥 Microsoft Edge
• 💥 Google Chrome
• 💥 FireFox
• 💥 Safari
• mobile (iOS/iPadOS)
• mobile (Android)
• not applicable
• other (enter in the "Additional environment details" area below)

Additional environment details

This isn't an SPFx development issue per se, but we're using:
SPFX version 1.4.1
Node 10.16.2

The server was just updated with 16.0.10417.20037

Describe the bug / error

We have a client using SPFx on classic publishing pages in SharePoint Server 2019. After applying the recent security patches, the SPFx web parts can no longer be edited. There is a React error in the console related to the sp-classic-page-assembly.js file. The full message is here: https://react.dev/errors/130?invariant=130&args%5B%5D=undefined&args%5B%5D=

Steps to reproduce

1. Edit the classic publishing page.
2. Click to edit the web part. The classic "configure web part" panel will open.
3. Click the "configure" button, which is supposed to open the SPFx web part property pane. Nothing happens, and an error shows in the console.

Expected behavior

Before the security patches, the web part property pane opened for editing.

[Amey-MSFT]

Hello @corriespondent,
Thank you for bringing this issue to our attention. We will look into it and get back to you shortly.

[Amey-MSFT]

Hello @corriespondent,
We were able to reproduce the issue, and we are investigating it. We have logged this as a bug, and our engineering team will look into it.
Thank you!

[Amey-MSFT]

Hello @corriespondent,
Apologies for the delay,
We were able to reproduce the issue, and we are investigating it. We have logged this as a bug, and our engineering team will look into it.
Thank you!

[nosololaura]

@Amey-MSFT and @corriespondent We have the same Issue, after same CU July 2025 Update

[nosololaura]

Any avaible information about this "bug"? Always can be reproduced or with some condition?

[mcalotoc]

Any news about this bug? @Amey-MSFT

[VesaJuvonen]

This is far from optimal and the issue has been shared with the owning on-premises team. I'm working on getting any updates from them on this, so that we could provide a public timeline to address this - but don't have that information currently.

If you or your customer has a direct Microsoft relationship, please open a ticket with them - so that the issue get's amplified also through the official support channels. I'll get back here as soon as have any news - hopefully getting and update on this soon, but can't unfortunately promise anything right now.