Symptoms

When clicking on any application form in the K2 mobile app, an error is displayed to the user "Sorry, something went wrong". When looking in the K2 mobile logs for the same action, the following error is seen:

Http Request(Error)
RETROFIT ERROR - Internal Server Error
 

Diagnoses

This is a problem with the way the K2Api site is hosted and which Application Pool was running the application. When hosting smartforms in a separate site in IIS from the rest of the K2 applications, there are two /K2Api virtual directories: one in the main K2 site and one in the K2 smartforms site. This behavior can occur when one of the /K2Api applications is being hosted under the Default Application Pool rather than the k2_net4 application pool.
 

Resolution

By moving the /K2Api application running under the Default Application Pool to the k2_net4 application pool and performing an IIS reset, this can resolve the issue. Application Forms in the mobile app are then accessible after this change. The resulting configuration change means that there are two /K2Api applications hosted in the k2_net4 Application Pool one for the K2 site, and one for the K2smartforms site.