SharePoint / SharePoint/sp-dev-docs
Debugging Form customizers causes weird URL behavior
@Ashlesha-MSFT is already working on this.
Since Mar 31, 2026.
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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
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 🤔
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Assessment
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