Hi AZBigDog, I suspect there is some kind of incomplete cleaning of session history files. Those are the files Firefox uses to recover from a crash or to implement the "Restore Previous Session" feature.

Does the message come up on a page with the option to restore a crashed session or does it come up in some other context?

Also, have you changed this setting:

(1) In a new tab, type or paste about:config in the address bar and press Enter/Return. Click the button promising to be careful or accepting the risk.

(2) In the search box above the list, type or paste sess and pause while the list is filtered

(3) Check the browser.sessionstore.max_resumed_crashes preference:

(A) Default value of 1 makes Firefox try one automatic crash recovery;

(B) Modified value of 0 makes Firefox skip to a screen asking if you want to perform a crash recovery.

We recommend not using 3rd party programs to clean Firefox as they could remove the wrong data.

jscher2000 said

Hi AZBigDog, I suspect there is some kind of incomplete cleaning of session history files. Those are the files Firefox uses to recover from a crash or to implement the "Restore Previous Session" feature. Does the message come up on a page with the option to restore a crashed session or does it come up in some other context? Also, have you changed this setting: (1) In a new tab, type or paste about:config in the address bar and press Enter/Return. Click the button promising to be careful or accepting the risk. (2) In the search box above the list, type or paste sess and pause while the list is filtered (3) Check the browser.sessionstore.max_resumed_crashes preference: (A) Default value of 1 makes Firefox try one automatic crash recovery; (B) Modified value of 0 makes Firefox skip to a screen asking if you want to perform a crash recovery.

Thanks for the suggestion. I tried it and then ran Wise Disk Cleaner but still got the same error, so it must be deleting something else that Firefox is looking for upon startup

I don't believe it is a cookie as it still shows 99+ cookies there after restating it.

AZBigDog said

Thanks for the suggestion. I tried it and then ran Wise Disk Cleaner but still got the same error, so it must be deleting something else that Firefox is looking for upon startup

I didn't suggest any changes, I asked about a preference setting.

Does the utility let you see a log of what it did?

jscher2000 said

AZBigDog said

Thanks for the suggestion. I tried it and then ran Wise Disk Cleaner but still got the same error, so it must be deleting something else that Firefox is looking for upon startup

I didn't suggest any changes, I asked about a preference setting.

Does the utility let you see a log of what it did?

I was talking about changing the "1" to a "0" in "browser.sessionstore.max_resumed_crashes" setting. Unfortunately that didn't seem to help. After WDC was ran again it still gave that same message about restoring tabs when starting FF. Might just install WDC as it leaves behind stuff in FF (cookies) anyway.

AZBigDog said

I was talking about changing the "1" to a "0" in "browser.sessionstore.max_resumed_crashes" setting. Unfortunately that didn't seem to help.

It wasn't meant to help. Using "0" means Firefox will always present the failed crash recovery screen instead of trying "1" automatic crash recovery first. I wanted to see whether yours was already set to "0".

Either way, if you are exiting out of Firefox normally (for example, using the menu button and then Exit) but at the next start Firefox thinks it needs to do a crash recovery, the most likely reason is that some session history files were removed.

You could take a look. This involves opening up your profile folder and after exiting out of Firefox, checking what session history files are there, then after doing a cleanup, seeing what was removed. Here's how:

Open your current Firefox settings (AKA Firefox profile) folder using either

• "3-bar" menu button > "?" Help > Troubleshooting Information
• (menu bar) Help > Troubleshooting Information
• type or paste about:support in the address bar and press Enter

In the first table on the page, on the Profile Folder row, click the "Open Folder" button. This should launch a new window listing various files and folders in File Explorer.

Leaving that window open, switch back to Firefox and Exit, either:

• "3-bar" menu button > Exit
• (menu bar) File > Exit

Pause while Firefox finishes its cleanup, and you should see these changes:

(A) In the profile folder

A new file named sessionstore.jsonlz4 should appear. This holds the windows and tabs from the session that just ended. Do you see that one?

If you have Firefox set to restore your previous session windows and tabs automatically, it's possible this won't be stored here, but instead in the subfolder under (B):

(B) In the subfolder sessionstore-backups

While Firefox is running, you would see these two files getting nearly real-time updates to your lists of open tabs and windows:

• recovery.jsonlz4
• recovery.baklz4

Normally at shutdown, those get removed when the file under (A) is created.

The folder also should have:

• previous.jsonlz4 -- tabs from the immediately previous session
• upgrade.jsonlz4-numbers -- session snapshots from auto-updates

Make a brief note of what you find, or screenshot them, then run WDC and see what gets removed (if anything).

Use one of these to close Firefox if you are currently doing that by clicking the close X on the Firefox title bar.

• "3-bar" menu button -> Exit (Power button)
• Windows: File -> Exit
• Mac: Firefox -> Quit Firefox
• Linux: File -> Quit