In WebDrawer 8.2 and 8.3 you might see the error message below...

This error reflects the fact that an error has occurred in the process of parsing an error message, so you have an error but do not know what it is. A better error message might look like this...

To fix this problem edit the hptrim.config file and add the uploadBasePath as seen below.  The uploadBasePath is not used by WebDrawer but the error handling in the underlying framework needs it. 

<hptrim 
    uploadBasePath="[Not Used]"
    ...