OMG, I was so dependent on this add-on, it is a must, but for what I assumed it update auto and a lost more than 1000 tabs needed for work and researching, is there a way to recover them? Even onetab page extension isn't working.

Edit:
this is how I got it working on firefox on POP_OS!, got to "/.mozilla/firefox/mbmm1a9s.default-release/extensions/" on my home folder and double click on "extension@one-tab.com.xpi" file, then it opened in firefox and gave permission to the onetab notification and voilá, it restored all my tabs again!

now backing up the urls to a txt file in nextcloud using the export function

They seriously need a more robust solution for saving data or backing it up to Nextcloud or smth!

I am now very dependent of OneTab. It saves so much RAM and organizes all my open tabs nicely. To my horror this morning all my saved tabs were gone. After hours searching for a solution I find here in the reviews that the solution is to disable and re-enable the plugin to make it come back with all saved tabs. I will give 5 stars if this marvelous plugin could make automatic backup copies of all saved tabs in a simple, plain .html file that is available immediately in case of some failure either from the browser or the extension.

1.36 on FF 80.0.01 lost all tab after restar,tested in two pc ，don't upgrade.This is the second time I have lost all tab, I will not use this plugin again

Muy buena aplicación pero debería de tener la opción de sincronzar las pestañas guardadas en los diferentes navegadores donde se utilice onetab.

This extension is invaluable to me. I was afraid that all of my tabs were gone with the last update. As others have pointed out, simply disabling and reenabling the add-on should fix the problem.

Works well. Does the job. Lost the tabs once but who knows. As for people complaining about the latest update 16/9 you just have to disable and re-enable to app to function..

The last update has a bug. I solved it by deactivating the extension and activating it

This is a really important addon for me and it is a desaster: After the last update all tabs are gone. >> There has to be some sort of backup for this - can you do it please! <<

For me the last update also broke this extension. All the tabs are gone.

The developer could have at least answered to one of the complaints and tell us whether only the GUI part is broken, but the information about the stored tabs is still kept somewhere in the profile (and if yes, then how to retrieve it), or all the information is lost completely.

After the latest update you have to remove the extension and add it again to make one tab work again in firefox. But you will lose all your stored tabs in the past.

I'm freaking out. I'm a dedicated OneTab power user. [Edit: Or was. I found out that Tab Stash can import OneTab data. At least I can restore my last bu.]

And it just died. Gone. Not in my right-click menu. Won't open in the browser, but Firefox does show the manage app page. Ugh, my last backup was four weeks ago. I'm crushed. So much research gone. That'll teach me.

The latest update requires to disable and reenable the extension to have it working properly.

Update broke OneTab. Going back to previous version.

This was an indispensable add-on for me until today (16 Sept. 2020). Today's update (v 1.36) has broken OneTab completely. I can no longer save tabs, nor can I get the OneTab page to open. I am using Firefox 80.0.1 running under Windows 8.1 Pro x64.
I was able to revert to v1.29 (which still works) on a Windows PC, but only by first removing and then re-adding OneTab, which resulted in the loss of all of my stored tabs. The instructions at https://www.one-tab.com/firefoxRestore are evidently outdated, as the indicated "simple-storage" folder under Windows 8.1 Pro x64 is empty, regardless of whether Firefox is running.
Having learned from my experience with the Windows PC, I disabled updates on my Ubuntu PC. This appeared at first to have the desired effect. However, when I started Firefox again after rebooting the system, OneTab was missing completely. I haven't found any instructions for recovering lost tabs under Ubuntu.
I have made exports of saved tabs on both machines, but they are a few weeks old. OneTab doesn't appear to have an automatic backup facility, and since it is unclear where its data now resides, I see no way to implement one.
Update: OneTab is working again as of th e new version, 1.39 (see developer response below), so I am upgrading my rating to 4 stars. I especially applaud OneTab's efforts to require the minimum permissions needed, although I would caution users to check the setting for reading tabs in private sessions, which is enabled by default.
The add-in is so useful that I would give it five stars, if:
1. The instructions at https://www.one-tab.com/firefoxRestore were updated. In case anyone is interested, OneTab appears to now store its data in an SQLite db in a folder named "idb" under \storage\default\moz-extension+++1297484c-254f-45f9-a970-69c5c1cc0f50^userContextId=4294967295
2. It would add an automatic backup/export feature. The HTML export/import works very well. How much trouble would it be to automatically store the export file? This could be an option to be done on each update of the list.
Judging by the posts my web search turned up, this isn't the first time a bug has caused OneTab users to lose data. Regardless of the problem's source, I am sure that many users would be glad of some such insurance.

Amazing

Great Add-On. I have a couple recommendations for the developers, but they're too good to mention here.

Excellent!