Logging into your GLPI installation from Gapp (A GLPI app) is not possible due to a blank screen.
Versions after 1.1.1 will show this message:
It seems your GLPI environment may be failing due to a plugin
Multiple factors may cause this issue but in the end, they all are related to breaking GLPI API authentication.
Disable all of your GLPI plugins and test Gapp again. If Gapp works then you need to find the offending plugin.
Know GLPI API breakers
We will list here any confirmed GLPI API Breaker plugins.
This issue has been reported a few times both at the My Dashboard and GLPI repositories:
You can apply this patch to fix it:
Not affected release: