Hey there! It's a bummer to hear about those blank tabs causing trouble. Don't worry, we'll get this sorted out. First off, the sudden appearance of blank tabs can sometimes be due to a glitch in the browser cache or an extension misbehaving. Let's start by trying a couple of things:

Clear your browser cache: Click the three lines in the upper-right corner, go to Library > History > Clear Recent History. Choose "Everything" in the time range and make sure "Cache" is checked, then hit "Clear Now."

Try Firefox in Safe Mode: This disables extensions temporarily. Click the three lines, then "Help" > "Restart with Add-ons Disabled." If the issue goes away, it's likely an extension causing the trouble.

If these steps don't do the trick, don't hesitate to reach out for more help. We're here to get your tabs back to their lively selves!

Were that tabs that you hadn't opened the previous session(s)?

Sometimes when restoring a previous session Firefox will create the tab but not show the address. I don't think I've ever seen an explanation for that, and it's hard to test because it's hard to cause on demand.

Does the following menu let you reopen any of the tabs you closed? Either:

• "3-bar" menu button > History > Recently Closed Tabs
• optional "Library" toolbar button > History > Recently Closed Tabs
• (menu bar) History > Recently Closed Tabs

Firefox creates numerous session history files as you work, but because most session history is only for the immediately previous session, it is unfortunately difficult to roll back further. When Firefox does an automatic update, it creates a snapshot of your session from that time, so perhaps one of those files could be useful. Here's how to mine its contents:

(1) Open your profile folder...

You can open your current Firefox settings (AKA Firefox profile) folder using either

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

In the first table on the page, find the Profile Folder row and click the "Open Folder" button. This should launch Windows' File Explorer listing the contents of your current profile folder.

(2) Copy out session history files

In your profile folder, double-click into the sessionstore-backups folder. Save all files here to a safe location such as your Documents folder.

(3) What files did you find?

The kinds of files you may find among your sessionstore files are:

• recovery.jsonlz4: the windows and tabs in your currently live Firefox session (or, if Firefox crashed at the last shutdown and is still closed, your last session)
• recovery.baklz4: a backup copy of recovery.jsonlz4
• previous.jsonlz4: the windows and tabs in your last Firefox session
• upgrade.jsonlz4-build_id: the windows and tabs in the Firefox session that was live at the time of your last update <= this may be the most interesting one

(4) Extract and View File Contents

These compressed files are a pain to view, so I created a tool on my website to list out their contents. If you want to try that, you can drag and drop it onto the large box on the following page, then click the "Scrounge URLs" button:

https://www.jeffersonscher.com/ffu/scrounger.html

If you don't get a list within 15 seconds, that probably means the script is caught in a loop. You may need to close the tab to avoid a tab crash and then try again in a new tab.

If you get a useful list, use the "Save List" button to archive it as a web page of clickable links for future reference, in case no other approach is successful.