Hi 

I have a user that has just switched to Lightning. When they try to compose email in activity timeline gets error:

Unfortunately, there was a problem. Please try again. If the problem continues, get in touch with your administrator with the error ID shown here and any other related details. An internal server error has occurred Error ID: 1057491293-40064 (2112433694)

However other users with same profile/lightning app are fine. Cant work out why he is any different or what its about. Any suggestions ? 

Thanks 

Andrew