Similar to an old closed discussion

[StoneD16]

My Thunderbird updated to Ver.52 on 4/7/2017. Ever since that date, when I hit SEND I get a pop-up saying :
ReferenceError: nsPreferences is not defined"
I can't figure out which Add-On or Plugin is causing it, but it also seems to save Sent Items in the INBOX. I was able to create a Local- Sent Folder to save all my 'Sents' from 5 email accounts. I'm fairly new to Thunderbird and didn't know how to go about getting a fix.I've had Firefox for years and donated. What can I do ?

[DanRaisch]

Does the same thing occur if you launch the application in Mozilla Safe Mode? http://kb.mozillazine.org/Safe_mode