Unable to add ISO in SolusVM 2 Client area: user_id: The field isn't allowed

Symptoms 

Unable to add ISO in SolusVM 2 Client area. The following error can be found in browser devtool:

CONFIG_TEXT: errors: {user_id: ["The field isn't allowed."]}
message:"The field isn't allowed."

Cause

SolusVM 2 bug with ID #SIO-5317 which was fixed in SolusVM version 2.0.0-30738

Resolution

Update SolusVM 2 to the latest mainline version.