Roundcube is giving server error with no logs. Strange AJAX response

Question

After an apache2 and php update, roundcube started to give Server Error dialogs. I checked the ajax responses and the data is received but with strange characters in the end.

{"action":"refresh","unlock":"loading1415016032431","exec":"this.set_unread_count(\"INBOX\",0,true,\"\");\n"}����������������

What could it mean?

Versions: Roundcube 0.9.5

apache 2.2.22

php 5.3.10

Ubuntu 12.04

Thanks!

Answer 1

As it turned out, all I had to do was to enable expires apache2 module.