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Error: Permission denied to access property "nodeType" #4183
Description
Prerequisites
- I verified that this is not a filter list issue. Report any issues with filter lists or broken website functionality in the uAssets issue tracker.
- This is NOT a YouTube, Facebook or Twitch report. These sites MUST be reported by clicking their respective links.
- This is not a support issue or a question. For support, questions, or help, visit /r/uBlockOrigin.
- I performed a cursory search of the issue tracker to avoid opening a duplicate issue.
- The issue is not present after disabling uBO in the browser.
- I checked the documentation to understand that the issue I am reporting is not normal behavior.
I tried to reproduce the issue when...
- uBO is the only extension.
- uBO uses default lists and settings.
- using a new, unmodified browser profile.
Description
When used in Firefox, inspector's console alerts on errors saying "Permission denied to access property nodeType".
The involved script is contentscript.js, and the errors always come from 2 different points (column:line) in this file :
1132:26 and 342:22.
This happens on most of websites.
A specific URL where the issue occurs.
https://www.w3.org/2000/svg (very basic page, no javascript)Steps to Reproduce
- Open Firefox (last version)
- type URL in the address bar
- Open the Inspector (Ctrl + Shift + I)
- Refresh the page
- Observe the logs in inspector's console
Expected behavior
Error should be masked as it doesn't bring any relevant information and is purely technical. uBO can't also do anything to solve it, as it only concerns Firefox' security policy.
Troubleshooting information
uBlock Origin: 1.75.0
Firefox: 159
filterset (summary):
network: 688856
cosmetic: 50052
scriptlet: 35862
html: 4269
listset (total-discarded, last-updated):
default:
user-filters: 269-28, never
ublock-filters: 55790-79, 4h.35m Δ
ublock-badware: 10557-40, 4h.35m Δ
ublock-privacy: 4170-18, 4h.35m Δ
ublock-unbreak: 2912-32, 4h.35m Δ
easylist: 83351-113, 4h.35m Δ
easyprivacy: 56960-21, 4h.35m Δ
urlhaus-1: 544945-11, 10h.4m
plowe-0: 3573-1055, 8d.9h.46m
FRA-0: 18457-272, 4d.10h.53m
ublock-quick-fixes: 772-13, 4h.35m Δ
filterset (user): [array of 269 redacted]
trustedset:
added: [array of 89 redacted]
userSettings: [none]
hiddenSettings: [none]
supportStats:
allReadyAfter: 13035 ms (selfie)
maxAssetCacheWait: 7484 ms
cacheBackend: indexedDB
Activity
gorhill commentedon Oct 31, 2026
I followed the steps-to-reproduce using
https://www.w3.org/2000/svgin step 2, and I cannot reproduce any error in the dev tools console.LupinIII commentedon Nov 6, 2026
I do have the exact same issue (at the exact same code location). It happens for all pages, like the above https://www.w3.org/2000/svg or example.com. I have observed this for a very long time already (so it's not just recent versions of uBlockOrigin).
The error at
contentscript.js:1132:26happens usually just once at page load, the one atcontentscript.js:342:22a few times at page load and then repeats about once a minute.I do have one other extension that also throws the same "permission denied" error: KeePassXC-Browser. Just mentioning it, in case there are any commonalities. Judging by the function names in the call stack trace it does seem to happen there on a DOM-observer handler as well.
Here are the call stack traces:
From KeePassXC-Browser:
gorhill commentedon Nov 6, 2026
If it also happens with other extensions, then this seems to be a browser-wide issue. Have you modified your browser’s ‘about:config’?