I am using Drupal 7.56, CiviCRM 4.7.20 and Mosaico extension 2.0-beta2.1494950412. When sending an email with a few images to ~950 contacts I get an Internal Server Error (500). Removing a few images and the email succeeds. The server is presumably running out of some resource but I have not been able to determine what it is. Is anyone else experiencing this issue? If so do you know what resource I need to increase (if indeed that's the problem)?

  • Your server logs are probably the best source of information. I'd start with the log for Apache (or whatever your web server is). If you don't find anything there, the CiviCRM or MySQL logs might have something useful. – universalhandle Jul 5 '17 at 14:48

The problem is caused by insufficient php memory. My php memory setting was 256MB and when I increased that to 512MB the problem was resolved. I don't know what setting would be 'correct' since I am not keen to retain php memory at 512MB.


Whilst increasing php memory solved the problem I was not comfortable in leaving the memory allocation just for Mosaico. So I throttled down the number of emails being sent at a time and reduced the php memory back and I have had no issues since that time. My settings are now php memory 256MB and I send 250 emails at a time.

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