Any chance this happens on first tab of freshly opened Firefox only? There is known bug where extensions fail to work on first tab. Similar issue: Matrix overlay numbers missing · Issue #95 · uBlockOrigin/uMatrix-issues · GitHub
Wow thanks. I wasn’t aware uMatrix issues were discussed at that page. This is definitely a first tab problem, thanks for pointing this out to me!
Does uMatrix support patterns with wildcard character in it (for ex: example.com *.example.org xhr allow )? I tried one pattern of this kind but, it didn’t work whereas, replacing *.example.org with * worked.
Wildcards are implicit, no need for asterisk - all subdomains are included.
@gwarser Thank you.
I wonder, why doesn’t explicit asterisk work?
In Google Chrome, one can set a keyboard shortcut to open uMatrix up (open uMatrix to the grid-view where one can allow/disallow items). There is no keyboard shortcut ability in Firefox.
Is the fact that there is no keyboard shortcut for Firefox a “Firefox bug” or a feature that gorhill has not implemented into the uMatrix version of Firefox?
This was Firefox bug for some time Firefox keyboard shortcuts · Issue #37 · uBlockOrigin/uMatrix-issues · GitHub but now it’s “not enough free time” bug 
I also don’t think Firefox support “Activate the extension” action for shortcuts.
To make sure I understood your post correctly: it is a “bug” with Firefox then, not something that has been left out of uMatrix?"
I dont know why I can’t open webpages anymore if uMatrix is enabled. I am on firefox 74 linux version.
I removed hpHosts from stock assets and it turns out the code was not prepared to deal with such removal, unlike uBO. It’s a code path that was never tested in uMatrix.
The workaround I have identified is:
- Open uMatrix’s dashboard
- Go to Assets pane
- Select or unselect one hosts asset
- Click “Apply changes”
- Revert change above, click “Apply changes” again
This should fix uMatrix until the proper fix is in the next release.
…I have reverted the removal of hpHosts for the time being, so possibly forcing an update of all assets would fix the issue as well. You should un-check hpHosts, it’s no longer served from the remote server, it will be removed again once uMatrix can deal with doing so without breaking.
https://www.reddit.com/r/uMatrix/comments/ftebgz/no_pages_load_on_firefox_unless_i_disable_umatrix/
uMatrix : Block entire Domain and its Subdomains.
Hi, i got following rules:
- yaunel.com * block
- yaunel.com frame block
- api.yaunel.com * block
- api.yaunel.com frame block
behind-the-scene api.yaunel.com * block
behind-the-scene yaunel.com * block
behind-the-scene yaunel.com frame block
but these do not block it 
How could i manage to block yaunel.com?
thx
uMatrix is off in behind-the-scene context.
My uMatrix addon has worked flawlessly for years. Then, in the middle of watching a YouTube video on Firefox 90.0.1 (latest), it auto-updated to version 1.4.2 and broke Firefox completely, cutting off all internet access. The only solution I have found so far is to disable uMatrix completely… which is a shame. I’ve restarted Firefox to no avail. I’ve attempted disabling, re-enabling and updating the rules lists from within uMatrix settings, but that doesn’t work either. (I don’t think they’ve been able to update because the extension is broken.) The official issue tracker doesn’t appear to accept new issue reports at present, due to the code being archived, so I’m posting here instead. Hopefully this major glitch can get picked up and addressed quickly.
I found a workaround on reddit.
I re-enabled uMatrix, and visited its preferences page, the “assets” tab. Then I selected “Update Now”. Then, after a while the following entries (Hosts files and Rulesets recipes) were displayed with a broken link icon next to them:
- Malware Domain List
- Malware domains
- Ruleset recipes for English websites
I disabled those entries, and now uMatrix is working again.
had the same issue. Disabling the broken assets under the “Assets” tab (those with broken link icons) fixed it for me too. uMatrix is working fine now. Appreciate the tip!