Unable to migrate or restore OneTab and its data
None of the available migration or restore methods are capable of preserving OneTab data. In every case I have tried, OneTab is missing from the add-ons in my new installation or profile. The only approach which achieved anything at all was to replace the entire .mozilla director under Ubuntu, but even this only displayed the OneTab page and its data on the first invocation of Firefox. Since the add-on was not present, the data was gone at the second invocation. However, repeating this process at least allowed me to export the OneTab data from *one* profile on the first invocation. Unfortunately, this method is completely useless under Windows, as are the recommended approaches of using Firefox sync (with sync turned on for add-ons) or replacing the contents of a newly created profile with the contents of an old or saved one. How can I properly backup and restore or migrate a Firefox installation, *including* my OneTab installation and data?
Opaite Mbohovái (2)
Meanwhile I have managed to migrate a complete Firefox installation, including OneTab and its data, from a Windows 7 account to a Windows 8.1 account by simply replacing the entire %AppData%\Mozilla\Firefox directory in th new installation with the corresponding directory from the old installation. This is simpler and more reliable than the recommended procedure of creating a new profile and copying over the contents of the old one. A further disadvantage of the recommended procedure is the need to dispose of the „corpses“ of the old profile(s).
The above procedure is still the best answer I have found, but success is not guaranteed. I have had cases where I have copied the old directory and have still lost OneTab (not just its content, but the plugin itself). This is particularly perplexing, as it tends to happen in caes where the profile in question was being synchronized through my Firefox account. The display of links in a OneTab tab on first invocation (described in my first post above) was evidently a relic of page content from the old profile which had not yet been refreshed. However, since the OneTab add-om was completely missing in the new installation, no refresh was possible and the tab was empty on the second invocation. Why wasn't the add-on and its settings (if not its data) restored by Firefox sync?