Forum response - After 66.0.4 update Add-ons appear unsupported or disappeared
If your Add-ons are appearing as unsupported or disappeared from your about:addons page please try these steps.
Their data is not lost because it is stored locally on your profile directory. (Bug 1549129). Re-installing the add-ons will recover the data:
- Go to https://addons.mozilla.org/firefox/.
- Search for your add-ons and install them individually.