UCI Dashboard not loading after the 2003.5 release

After being updated to the 2003.5 release, a dashboard that has a subgrid which has been configured to use a custom control (e.g. an editable grid) does not load in UCI.

The dashboard may be stuck with a loading spinner, or it may show a generic error message ("Something has gone wrong. Check technical details for more details").

This issue is caused when there's a subgrid on the dashboard that has been configured to use a custom control, but not for all form factors. When there's a custom control configuration, but not all form factors have one, then there ends up being an unhandled null exception that prevents the dashboard from loading.

E.g., the control configuration may look something like this:

[Asset 4558631]

Alternately, this may be caused by a control configuration that isn't used for any form factor, such as something like this:

[Asset 4558638]

This issue was tracked by the following work item:
Bug 1791995: Custom controls don't render on dashboards if they're not defined for every form factor

The bug is fixed in the 2004.3 release. However, customers can work around the issue sooner by adding a control configuration for all form factors.

In some cases the custom control being used may not allow being set for all form factors (e.g. editable grid cannot be set for phone form factor) or the customer may want to use the default read only grid for some form factors. In those cases this work around is still applicable because the read only grid may be chosen as a custom control configuration as well.

E.g., the first control configuration from the "Cause" section above can be changed to something like this to mitigate the issue:

[Asset 4558634]

Alternately, if this issue is happening due to a control configuration that isn't used on any form factor, that control configuration can simply be removed.