How do I debug a difficult-to-reproduce crash with no useful call stack?

Question

I am encountering an odd crash in our software and I\'m having a lot of trouble debugging it, and so I am seeking SO\'s advice on how to tackle it.

Answer 1

I'm not 100% sure, but from the image you provided I believe that somewhere along the executing you're trying to access a object in a TList that is NULL. i.e.:

AList[Index].SomeProperty/SomeMethod/etc. <-- error if (AList[Index] == NULL)

Regarding debugging and finding the actual place where the exception is raised is never an easy task especially when there's not much information or it is hard to reproduce, in this case I usually:

• go step by step from the main form's execution(if no exception until there)

• while going step by step, if I find any unsafe code I put it between try...except and conditions for indexes(if I have arrays, lists, expected values to be passed, etc.)

• if the above fails to find the issue, check if some libraries are failing

• use Eureka log, it sometimes fail as well(very few times) but it usually points you in the right direction

I have had numerous issues similar to yours and I can tell you that the issue was almost a extremely easy to fix, however when the error pops, I did not get a "point near" the error.