UPDATE: I have my original browser info in place with history and links in toolbar. I now get the about:sessionrestore window back but still with a blank browser screen and no buttons to click in the middle to restore previous FF browser windows with tabs.

There are NO other options to restore from in the usual places including Library or History.

Did you check the upgrade files in the sessionstore-backups folder in the profile folder ?

You will normally find these files in the sessionstore-backups folder:

• previous.jsonlz4 (cleanBackup: copy of sessionstore.jsonlz4 from previous session that was loaded successfully)
• recovery.jsonlz4 (latest version of sessionstore.jsonlz4 written during runtime)
• recovery.baklz4 (previous version of sessionstore.jsonlz4 written during runtime)
• upgrade.jsonlz4-<build_id> (backup created during an upgrade of Firefox)

You can copy a file from the sessionstore-backups folder to the main profile and rename the file to sessionstore.jsonlz4 to replace the current file (make sure to backup the current sessionstore.jsonlz4).

You can create a new profile as a quick test to see if your current profile is causing the problem.

See "Creating a profile":

• https://support.mozilla.org/en-US/kb/profile-manager-create-remove-switch-firefox-profiles

If the new profile works then you can transfer files from a previously used profile to the new profile, but be cautious not to copy corrupted files to avoid carrying over problems.

• https://support.mozilla.org/en-US/kb/recovering-important-data-from-an-old-profile

I have those 3 files and have tried a new profile but nothing loads. I have the orginal profile in place and trying to replace backup with current session.

Have tried Firefox session scrounger and can see my tab links but keeps crashing before it is done so havent been able to extract.

You can possibly use this code in the Browser Console to decompress a compressed LZ4 file. To enable the command line in the Console:

• select "Enable browser chrome and add-on debugging toolboxes" in the developer tools settings
• https://developer.mozilla.org/en-US/Tools/Settings

javascript:/*DECOMPRESS LZ4*/(function(){async function decompressFile(oFilePath,nFilePath){let jsonString=await OS.File.read(oFilePath,{compression:"lz4"});await OS.File.writeAtomic(nFilePath,jsonString);}var fu = Cu.import("resource://gre/modules/FileUtils.jsm").FileUtils;var fp = Cc["@mozilla.org/filepicker;1"].createInstance(Ci.nsIFilePicker);fp.init(window, "Open File", Ci.nsIFilePicker.modeOpen);fp.appendFilter(".*LZ4* Compressed Files","*.*lz4*");fp.appendFilter(".LZ4 Compressed Files","*.lz4");fp.displayDirectory=fu.File(OS.Path.join(OS.Constants.Path.profileDir,""));fp.open((aResult)=>{if (aResult==Ci.nsIFilePicker.returnOK){if(fp.file.exists()&&fp.file.isFile()&&fp.file.isReadable()){var oldfile=fp.file.path;var newfile=oldfile+".json";try{decompressFile(oldfile, newfile);console.log("Saved as: \"" + newfile + "\"");}catch(err){console.log(err);}}}else{console.log("<canceled>");}});})()

I copy this into the console window?

Yes, once you have enabled the command line in the Browser Console (so not the Web Console) then you can paste this JavaScript code in the command line and press the Enter key to run the code. Note that you may have to type some text to enable pasting.

I did end up with a decompressed file .son file about 300mb in size. What would be next?

Also, I was able to extract tab links using ff session scrounger by not staying on the site, I had to be on another tab so it wouldn't crash. So I have been able to recover 99% of my browser window and tab info, so I'm safe with that, but would still like to have it repopulate in Firefox if possible without having to go through nearly 1800 links and rebuild my browser windows by topic.

I have tried using the previous and backup copies but they do not populate or show any sign of existing in new session.

Suggestions?