I started getting a similar error in Firefox yesterday trying to install an extension from the Add-ons site.

When I researched old threads, what seemed to help most people was the most drastic approach, which was to Reset/Refresh Firefox or create a new profile. I wasn't ready for that.

I tried removing the extensions.ini and extensions.json files so that they would be regenerated, but that didn't solve the problem for me.

Hopefully you (and I) will get some additional suggestions.

I'm going to take a detour from Thunderbird, but I'll get back to you, I promise.

It finally occurred to me to check for error messages in Firefox's Browser Console. When the extension installation failed, it shows these messages (shortened for posting):

1436479398851 addons.xpi ERROR Failed to remove file {PROFILE}\extensions\trash\adbhelper@mozilla.org\win32\adb.exe: [Exception... "Component returned failure code: 0x80520015 (NS_ERROR_FILE_ACCESS_DENIED) [nsIFile.remove]" nsresult: "0x80520015 (NS_ERROR_FILE_ACCESS_DENIED)" location: "JS frame :: resource://gre/modules/addons/XPIProvider.jsm :: recursiveRemove :: line 1317" data: no]

1436479398852 addons.xpi WARN Failed to install {TEMP}\tmp-ap9.xpi from https://addons.mozilla.org/firefox/downloads/latest/376953/addon-376953-latest.xpi?src=dp-btn-primary: [Exception... "Component returned failure code: 0x80520015 (NS_ERROR_FILE_ACCESS_DENIED) [nsIFile.remove]" nsresult: "0x80520015 (NS_ERROR_FILE_ACCESS_DENIED)" location: "JS frame :: resource://gre/modules/addons/XPIProvider.jsm :: recursiveRemove :: line 1317" data: no]

1436479398854 addons.xpi WARN removeActiveInstall: could not find active install for https://addons.mozilla.org/firefox/downloads/latest/376953/addon-376953-latest.xpi?src=dp-btn-primary

I started with the first point. After exiting completely out of Firefox, I drilled down to that "trash" folder and renamed it xxtrash to hide it from Firefox. After restarting and trying the install again, it went completely normally.

I have no idea whether your Thunderbird is stuck trying to delete an extension you wanted to remove, but you could check for errors in the Error Console. It is available on the Tools menu, if you do not ordinarily display the menu bar, a tap on the Alt key or F10 key should display it temporarily.

By the way, the extensions folder has a subfolder named staged that probably contains the pending install. As part of my troubleshooting last night, I ended up renaming that folder to unstaged because there seemed to be some confusion about whether I was updating or adding a new extension. You might try that and then install Lightning from the Add-ons site, keeping an eye on the Error Console.

Instead of reinstalling via Add-ons: Get Add-ons, I succeeded by downloading the XPI file and then in Add-ons, clicking the gear and choosing Install Add-on From File. At the prompt, I restarted Thunderbird, and the calendar was installed once again!

It still did not install. I see the progress bar and it says installing but it shows a small amount of green and freezes. Afterward it says to restart Thunderbird. Then it says no extensions are installed. See screenshots file attached.

See if this helps. https://support.mozilla.org/en-US/questions/1097411#answer-814160

For Thunderbird 38.5.0 the corresponding version of Lightning is 4.0.5.

christ1 said

See if this helps. https://support.mozilla.org/en-US/questions/1097411#answer-814160 For Thunderbird 38.5.0 the corresponding version of Lightning is 4.0.5.

No luck there either. Here is the latest screenshot where it has the top red error bar that indicates that it is a file access error. Do you think the logs will give the details? Also I cannot find Lightning 4.0.5 anywhere. Are you sure it exists?

No luck there either.

Please explain in detail the steps you did.

Also I cannot find Lightning 4.0.5 anywhere. Are you sure it exists?

It is my understanding Lightning 4.0.5 ships with Thunderbird 38.5.0. On AMO version 4.0.4.1 is still being offered, which will do as well.

christ1 said

No luck there either.

Please explain in detail the steps you did. ___________________________________________________ I have tried to install every way possible. Now only installing from file with antivirus shutdown. I have gone into adminstrator account and uninstalled and reinstalled thunderbird. This issue seems to involve permission to write to a file but I cannot find out what file is blocking the installation. The red bar at the top of the screenshot attached is the culprit. Whenever I do not get that screen I get the normal response to restart thunderbird and then it asks me to restart again at which time it removes itself from the addons menu. Hope this helps. Do you know where the error log is located?

I have tried to install every way possible.

That doesn't mean anything.

From your unspecific answers I still have no idea whether you did follow the suggestions or not. https://support.mozilla.org/en-US/questions/1097411#answer-814160 Please confirm.

If you didn't do any of the steps please explain why not or what you did do instead. Please be specific.

I have followed the instructions in every thread I could find now for several months and nothing addresses the file permission issue. I am not sure exactly what you mean by specific. I have installed every way that I found in the forums. With and without antivirus enabled. Used Administrator account and uninstalled and reinstalled thunderbird. Removed all of the extensions and still cannot make it work. I used to have it in an older version for thunderbird. Let me know if you need anything more specific. It may help to find some kind of error log but I do not know where to look for it.

I give up.

1. Tried normal install 2. Tried install from file 3. Tried both with antivirus shut down 4. Tried from Administrator account all 3 above as well as: 5. Tried uninstalling and reinstalling Thunderbird 6. Set full access permissions for everyone and tried all of the above. 7. Deleted everything in extensions folder and tried all of the above 8. Tried reinstalling Thunderbird as Administrator. Probably tried other things as well but do not remember. The issue is that the addon cannot write to the necessary file. Hope this helps.

I'm not a Thunderbird expert, but unless there is a problem with your file system, maybe the Thunderbird installation is suffering some corruption. Just outlining an approach, and issuing all disclaimers and warnings (backing up the address book -- and messages too if you have a POP setup, make notes on any message filters you created), you might consider uninstalling Thunderbird and then manually deleting both the profile folder and the program folder as well if that still exists. Then try a normal reinstallation/restoration of everything.

The start-from-scratch approach is a radical solution, but you have already tried so many of the usually-recommended measures.