Symptoms

After upgrade from 4.6.8 to 4.6.9 forms are getting 500 errors - combinedresources.ashx seems to be the error.
 

Diagnoses

This type of error will not allow the K2 Smartforms Runtime forms to load. Running a browser network trace will show the error itself.
 

Resolution

Applying the following workaround will help the forms render properly:

In the smartforms Runtime web.config file located in tinstall drive]:Program Files (x86)K2 blackpearlK2 Smartforms Runtime, make sure that the following properties are set as seen below on all K2 nodes:

<add key="UseBundledFiles" value="false" />

<add key="Forms.PostRenderCombining.Enabled" value="false" /> 

After these changes are made, save the web.config files, and do a K2 Service restart and an IIS reset on all K2 nodes.