To update, it's not updating to the session I want, it just updating to the last used session, which is reddit at the moment. My session lof is giving me "1774104610413 SessionStore ERROR NotReadableError when reading session file: clean: NotReadableError: Could not read `C:\Users\short\AppData\Roaming\Mozilla\Firefox\Profiles\5fy0bc78.default-release\sessionstore.jsonlz4': could not decompress file: invalid LZ4 header: wrong magic number: `00 00 00 00 00 00 00 00 00 00 00 00' (NS_ERROR_FILE_CORRUPTED) No traceback available" when I try to load it. it's directly from a restore point found with ShadowExplorer

Did you check the content of the file backup file?

Are you sure that the file is valid and not corrupted or only contains null bites? Did you place the file at the main level in the profile folder? You may have to rename the sessionstore-backups folder temporarily

Here is a script for the Browser Console (not the Web Console) to decompress LZ4 files using IOUtils. https://gist.github.com/jscher2000/4403507e33df0918289619edb83f8193

• https://firefox-source-docs.mozilla.org/devtools-user/browser_console/

I'm getting this. And I have no idea how to check if the file is null. All of my history is there, I just have no indication of what tabs were open as I had multiple windows and tab groups active at once.

I think it may be corrupted, I opend the file in notepad. The new JSONLZ4 opens with text. The old one is blank, but there are what apears to be invisible characters that are highlightable. Unless all of the data has been turned into spaces. File is 3535kb for added info.

Try this code.

async function copyFile(inpFile, outFile) {
 var data = await IOUtils.readUTF8(inpFile, {decompress:true});
 await IOUtils.writeUTF8(outFile, data, {compress:false});
}
var fp = Cc["@mozilla.org/filepicker;1"].createInstance(Ci.nsIFilePicker);
fp.init(window.browsingContext, "Open File", Ci.nsIFilePicker.modeOpen);
fp.appendFilter("Bookmarks/Session (.jsonlz4)","*.jsonlz4");
fp.appendFilter("Search Engines (.mozlz4)","*.mozlz4");
fp.appendFilter("Add-ons Files (.lz4)","*.lz4");
fp.displayDirectory=FileUtils.File(PathUtils.join(PathUtils.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.replace(/([.]moz)?lz4$/i,"")+(/lz4$/.test(oldFile)?"":"lz4");
    try {
      copyFile(oldFile, newFile);
      console.log("Saved as: \"file://" + newFile + "\"");
      prompt("Saved as:\n" + newFile, "file://" + newFile);
    }
    catch (err) {console.log(err);}
  } else {console.log("<ERROR>");}
  } else {console.log("<CANCELED>");}
});