Do any of you know what could cause this error? A Catchable

Hello, Do any of you know what could cause this error? A Catchable fatal error: Object of class WP_Error could not be converted to string in (link) ?

It is happening on Mobile phones but only for 2 users that have Author permissions. But no other Author users have experienced the issue and as an Admin, I have not be able to replicate the issue either. Any other help or suggestion would be great.