On Firefox, my favorite add-on is Tree Style Tabs (download), because
- you can see all of your tabs and their names
- tabs have hierarchy (parent > children > grandchildren)
Once you use it, you will always want to use it, especially at work. But if you get the error message “failed to get permissions to create bookmarks“, you need to grant permissions to the add-on. This is not straightforward. The notification will probably be cutting off some of the words! But if you got here, this is how you do it.
Go to Add-ons > Extensions > Tree Style Tabs > more.
You should see this, so check the checkbox next to “Allow to create bookmarks”
You might get another error message! This is because this add-on’s preferences page cannot request access to the bookmarks. So, you now need to click on the add-on’s icon in your toolbar:
And follow the prompts there. The confirmation dialog will likely appear on the top left of your browser window!
Man and Keyboard 
Your solution for saving Tree Style Tabs into bookmarks, dated January 23, 2018, suggests using the TST icon on the TST toolbar to grant permission. However, there are no prompts to follow, only a checkmark next to TST in the TST icon’s dropdown menu. (W7 Pro, 64bit, FF 60.0.2) Have you reached TST developer through Github?
I have not tried installing TST on Windows, just Mac. I have not reached out to the developer.
Thanks. On the initial reading of your comments, it was not clear what platform you use.
I fixed this by deleting Development -> requestingPermissionsNatively -> {“permissions”:[“bookmarks”]}.