Hi Hristo,

first of all that doesn't seem right - it shouldn't behave this way. But please remember that "session management" is marked as an experimental feature and that it's in beta. So you have to use it on your own risk. I have never tested it on a window with 500 tabs...

Now to solve your issue : Can you please try to open the tab manager in its' own tab ( right click on the icon and "Open in own tab" ) and then try restoring the sessions from there? And then see if that works?

Edit: Glad it worked for you! It seems the popup gets closed half-way when sending the request to the background page - maybe the background page gets killed because the popup was closed? Going to investigate this for one of the next updates! Thank you for the update and confirming the work-around!

Best,
Markus