What does "A custom control callback raised an exception" mean?

[GUI Guy]

Started getting this error today when compiling my CVI GUI. I didn't change any of the callbacks, in fact the source file didn't change though a header file did, but nothing that could point to this error.

[Wim S]

Hello Alex,

are you compiling on another machine? Or are you using another CVI version?

[GUI Guy]

Thanks for replying Wim S.

Same machine, same version (CVI 7.1). I have seen this error in the past, but it "went away" somehow. I'll try backtracking to see what causes it. Since this is an NI CVI error, it should have some documentation as to what it means.

Alex

[Mert_A.]

Hi Alex,

This just means that somewhere in a callback function for a control, some exception was thrown and not properly handled.  This error always indicates a bug (or at least bad handling of an unexpected state), whether in user code or the CVI environment.  It is not clear what change may have triggered this error.  Your best bet (as is generally the case) is to take a hard look at exactly what changed since you started seeing the error.

Mert A.
National Instruments