Article ID: 116059, created on May 8, 2013, last review on May 11, 2014

  • Applies to:
  • Plesk for Linux/Unix


The opening Horde webmail interface produces only a blank screen. No errors are being reported.


This problem may be caused by an enabled PHP APC (Alternative PHP Cache) extension and by the module's configuration being incompatible with Horde webmail.


Open the file /etc/php.d/apc.ini and check the value of the parameter apc.include_once_override. It should be set to "0" (zero):

apc.include_once_override = 0

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