Affected Products

Message

Null Reference Exception Error related to the Crestron Q-SYS V4.x module set.

While stating the exact reason behind why this issue exists involves some conjecture at this point, we do know that the issue can be traced as far back as Q-SYS Designer 5.2.x. which pre-dates the introduction of the Crestron V4 series Q-SYS modules.

At best there appears to be an issue with how well the Core module handles the initial connection to the Core.  There may also be other issues at play.  Without the ability to investigate the internal workings of the Core module there is really no definite way to know for sure.

Definition

In other troubleshooting notes related to the Crestron Q-SYS V4.x module set, the often seen Null Reference Exception Error was mentioned.  In general, the message, when it occurs, is usually on start-up of the Crestron program, and may be related to the Q-SYS Core Module and its operation, and sometimes related to other issues (i.e. JSON-RPC response handling).

Because it occurs at start-up of the Crestron program and during its interaction with Q-SYS, it means that the part of the Crestron module that communicates with the Core has stopped working.  Thus, that error in itself can prevent the Crestron control system from even communicating with the Q-SYS Core.

In examining this issue it seems:

1. The greatest impact happens when a User/PIN is setup on the Core
2. It only happens when the Crestron program is loaded or restarted, or when the Crestron processor is restarted.
3. It does not happen when the Q-SYS design is re-started/re-pushed, or the Core rebooted--which presumes the Crestron program is already running.

The greatest impact means the Crestron system will not communicate with Q-SYS.  There will be no controls working, nor feedback from Q-SYS.

Solution | Workaround

If there is no User/PIN, the impact is mitigated.  The error does interestingly still show up.  But the Crestron program appears to continue to try to re-push control-related information.

Thus, the quickest solution is not to use User/PINs.

Alternatively, a quick re-push of the design file, or a reboot of the Core.  After all, that was just done to the Crestron program.

To be clear:  THIS IS NOT A Q-SYS ISSUE.  The Null Reference Exception Error is purely on the Crestron side, it’s response to messaging it receives from Q-SYS (or doesn’t receive) at the appropriate time that it expects it.