What version of Firefox are you running?
Some users have difficulty installing extensions due to the redirect between the initial download address and the content distribution network (CDN). This seems to be blocked on their systems by security or filtering software.
For the first one:
For the second one:
Are you able to access the “cdn” links?
Hi.
For both CDN i get the same. I right-click a CDN link and select open in new tab, in new tab i get this message:“F irefox
has prevented this page from asking if it can install software on your computer”.
If i go to second tab, select URL of a CDN link and tap enter, i get this “The addon downloaded from this site could not be installed because it is probably corrupted”.
That’s normal, only certain sites have built-in permission to install add-ons. You can try giving permission if you trust the source.
If you try right-click > Save Link As, can Firefox download the XPI files successfully?
Yeah, i can save it as xpi but when i move it to firefox window, i get the same message again - corrupted file.
July 28
tedomedo:
I right-click a CDN link and select open in new tab, in new tab i get this message:“F irefox
has prevented this page from asking if it can install software on your computer”.
That’s normal, only certain sites have built-in permission to install add-ons. You can try giving permission if you trust the source.
If you try right-click > Save Link As, can Firefox download the XPI files successfully?
This problem is in the current release, Firefox 68.0.1?
Perhaps there would be a more detailed error message in the Browser Console (Ctrl+Shift+j, on Mac: Command+Shift+j). If you open that window, click the trash can at upper left to clear current messages, then try to load the file in the regular window, then switch back to the Browser Console, is there any additional information available?
These are error messages for cookie auto delete:
1564431959671 addons.xpi WARN Please specify whether you want browser_style or not in your options_ui options.
1564431959679 addons.xpi WARN Add-on CookieAutoDelete@kennydo.com is not correctly signed.
1564431959679 addons.xpi WARN Invalid XPI: signature verification failed
I set xpinstall.signatures.required back to default but it doesn’t help.
Verifying extension signatures shouldn’t be a problem in Firefox 66.0.5 or later unless that file really did get corrupted in download.
What version of Firefox are you running?
60.0.1
I don’t want newer version because newers versions “eat” more RAM. Also some good old addons aren’t compatible with newer versions.
NOW you tell me, after all this, that you are using a version that isn’t fixed?! I’m not happy you wasted so much of my time when your solution was so simple:
You can install the Extended Support Release of Firefox 60 – Firefox 60 with 9 more months of security patches – from the following page:
You’ll need to click the Firefox 60 link at the upper right of the list before downloading.
More info on ESR: https://support.mozilla.org/kb/switch-to-firefox-extended-support-release-esr
Go here: https://addons.mozilla.org/sl/firefox/addon/cookie-autodelete/versions/
Current version of Cookies Auto Delete should work for Forefox 59+. If this isn’t correct, edit text on https://addons.mozilla.org/sl/firefox/addon/cookie-autodelete/versions. Do this with current version of all addons. Of course, you’re lazy, you rather piss us off with text “can’t be install because it’s corrupted”. Such message looks more like firefox’ bug.
Hi all, a friendly reminder personal insults are not welcome on this forum per Mozilla’s Community Participation Guidelines.
I’m freezing this thread to give folks some time to cool off.
@tedomedo, this problem is patched in ESR 60.0.2. You need to upgrade to that version to get the patch. You can try to apply this patch as an extension though I’m not sure it will work on ESR.
This topic was automatically opened after 24 hours.
So you can confirm that this was Firefox’ bug?
Most extensions published before May 4th were signed with an older certificate that expired on May 4th. To use those older extensions after May 4th, you need to install a new certificate into Firefox and that substitutes for having to update every one of those extensions.
This new certificate is included in Firefox 66.0.5+, and Firefox 60 Extended Support Release 60.6.3esr+.
Some articles about why this problem occurred and what was done about it:
I was also having this issue today when I was released my own extension’s new version.
The latest version was published but I couldn’t upgrade/reinstall my own extension.
I was also getting the same “Installation aborted because the add-on appears to be corrupt” error.
But the extension worked flawlessly in debug mode (temporary installation during development)
FIX:
The issue was, system time was out of syc for some reason. As soon as I synced the time correctly, the extension installed.
If your system time is correctly synced and still getting the same error, keep looking for the solution 
This problem also appears because some devs have not updated the description of their add-on, and the requirements are not accurate.
So addons.mozilla.org lets the browser download the file even if your FF is not compatible with it, and the error message appears when it tries to install it, mostly because the extensions uses the api WebExt, I think.
I recently got this error with an extension that was supposed to require FF 48.0 and later but obviously it required FF 57 at least, because I’ve been able to install it with the latest version of FF ESR but not with FF 56. And it was not the fist time.
I don’t think developers should have to test on unsupported versions of Firefox, although it would be considerate to update the minimum version when using a new API that might not be supported by the latest ESR.
Developers should just update the requirements for their add-ons on the download page.
For example, here, you can see the different versions, back to 2017, and all of them have the same requirement (i think it’s by default automatically set by the add-ons website with a new upload) and it’s not accurate.
The add-on page checks the user’s FF version, and if the version required is not accurate it will let the download occur, and lead to this error, or even install the add-on, but it will not work.
This happened to me several times.
tedomedo: