I am running a development system under Joomla and IIS with CiviCRM 5.19.1 (5.19.0 had the same issue). When using API Explorer 4 I get windows like this. enter image description here

Under LAMP, the window makes sense. enter image description here Any suggestions?

  • Looks like something is wrong with angular in your browser or civicrm installation. Nov 13, 2019 at 8:33
  • Thanks @JaapJansma-CiviCooP. Where does angular live? …/administrator/components/com_civicrm/cvicrm/ang? Nov 13, 2019 at 11:35
  • Multiple sources and combined and stored in a cache. I am not a joomla expert. But in drupal it helps to clear the cache, and empty sites/default/files/js folder. How that works in Joomla I dont know. Nov 13, 2019 at 14:57

1 Answer 1


The problem was caused by IIS Request Filtering Hidden Segments. By default IIS has a hidden segment called bin. API Explorer 4 attempts to get JavaScript from


Notice the bin folder name. Removing the bin Hidden Segment cured the problem. Security isn't an issue - the web site is only accessible in the local environment.

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