Back up failure

Hi there,

Details: Moodle version 2.6.3 Essential Theme

I am trying to back up my site but it always stalls at around 95%. One time it gave me an error message but I did not grab a screen shot and it's not given me a message with subsequent back up attempts. 

I have looked at the site in Debug mode and the errors shown are pasted below. I am not a programmer but assume this is why the backup is failing, 

Can anyone advise: 

• Whether this is the likely reason my backups are failing
• Whether there's an easy fix (something I can do) or if it's serious/complex and I should seek prof help
• Should I just update the Essential theme, as this looks like where the errors are originating. If so, how do I do this? 
  

thanks!