SharePoint / SharePoint/sp-dev-docs

Debugging Form customizers causes weird URL behavior

Open
#10,747 4 comments 2 reactions 1 assignee View on GitHub

@Ashlesha-MSFT is already working on this.

Since Mar 31, 2026.

area:spfx-extensions sharepoint-developer-support status:tracked type:bug-confirmed
Dominant language
PowerShell
Stars
1.4k
Forks
1.1k
Avg merge
4d 12h
Merged PRs (30d)
12

Description

Target SharePoint environment

SharePoint Online

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

Edge Version 146.0.3856.84
SPFx 1.17.2

Describe the bug / error

When I'm debugging an SPFx form customizer and call the this.formSaved() at then end, I'm returned to the list, and faced with this error

Image

Looking at the URL, it did indeed drop my debug=true&noredir=true&debugManifestsFile=https://localhost:4321/temp/manifests.js - however when I go to re-add it manually it starts to get a bit wonky, I start with this:

/AllItems.aspx?FilterField1=LinkTitle&FilterValue1=FL-160&FilterType1=Computed&viewid=e84c894b-84d9-442e-8e1f-a38924e6429d&startedResponseCatch=true

Append the query paramaters needed

AllItems.aspx?FilterField1=LinkTitle&FilterValue1=FL-160&FilterType1=Computed&viewid=e84c894b-84d9-442e-8e1f-a38924e6429d&startedResponseCatch=true&debug=true&noredir=true&debugManifestsFile=https://localhost:4321/temp/manifests.js

But then get redirected to this (encoding, sure, that's fair)

AllItems.aspx?FilterField1=LinkTitle&FilterValue1=FL-160&FilterType1=Computed&viewid=e84c894b-84d9-442e-8e1f-a38924e6429d&startedResponseCatch=true&debug=true&noredir=true&debugManifestsFile=https%3A%2F%2Flocalhost%3A4321%2Ftemp%2Fmanifests%2Ejs

And still get the error, however, if I then refresh the page, the error goes away, and I can now keep on my debugging experience.

Steps to reproduce

See above

Expected behavior

Expected behavior (how it used to work) - is that my debugging session stays alive while navigating in the same tab.

The issue seems to be related to the rollout of the new developer toolbar, as I've only started seeing it after that rolled out 🤔

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Assessment

This issue has not been assessed yet.

Get new issues in your inbox

A short digest of beginner-friendly GitHub issues.