When using the Set Attribute Task to post a value to an attribute which triggers a script, the user always sees the following message
The operation is successfully completed.
This message is encountered even if the task posts a value which triggers a custom script which has encountered an error.
Debugging on the script confirms that the error message is encountered, but it is not displayed as expected in the Active Roles Web Interface.
Currently, the only known workaround is to avoid the use of the Set Attribute Task command.
If performing a triggered operation which might encounter an error, it is suggested to embed the triggering attribute into a Form in the Active Roles Web Interface instead of using the Set Attribute Task command.
Waiting for a fix in a future release of Active Roles.