I've set my Mozilla Firefox to restore my previous session every time I open the browser. Today all of a sudden more than half of my tabs appear as New Tab and they are empty (about:blank) even though it was fine the last time I accessed them several hours ago. The solution of switching sessionstore backups file won't quite work here because the most recent one is about a week old. I installed Session Manager add-on but it loads and reads session the same with all the lost tabs as about:blank, even the previous.js session file. (Though I probably made a mistake that I closed Firefox when it first appeared like that, then closed it, then reopened and closed again in hope that it was just a glitch and the browser would normally display all the tabs once again because I've never experienced specifically this kind of issue before, so probably the original previous.js file got replaced by the system the next time I reopened browser with all the lost tabs). I also tried Web-developed Scratchpad tool with the script but it also doesn't display the links or any information of those "New Tabs", only like this: "Not available about:blank ^ window 1 tab 146 entries 11" Lastly I renamed previous.js file to .txt file and all the lost tabs (that show up as empty New Tabs now) appear with their specific number and data but basically the line is like this: {"entries":[{"url":"about:blank","charset":"","ID":3579944675,"docshellID":149,"docIdentifier":410,"persist":false}],"lastAccessed":1481047073742,"hidden":false,"attributes":{},"userContextId":0,"index":1,"userTypedValue":"","userTypedClear":0,"image":""} What should I do, how can I fix this issue?