XML Parsing Error: undefined entity, not been able to open my Thunderbird.

Question

Not been able to use Thunderbird since from 2 days.
The error is: XML Parsing Error: undefined entity Location: chrome://messenger/content/messenger.xhtml Line Number 905, Column 3:

Using OS : Windows 10

Answer 1

XML random errors are very common, you can easily fix all these with your own. Just follow these simple steps.

1. Copy the 'Local Folders' folder from my old profile to the new profile. 

2. Next, upgrade to a later version