How to fix "'System.AggregateException' occurred in mscorlib.dll"

Question

I'm receiving an unhandled exception while debugging, and the program stops executing. The debugger doesn't show me the line so I don't know what to fix.

An unhandled exception of type 'System.AggregateException' occurred in mscorlib.dll

Additional information: A Task's exception(s) were not observed either by Waiting on the Task or accessing its Exception property. As a result, the unobserved exception was rethrown by the finalizer thread.

Cannot obtain value of local or argument '<this>' as it is not available at this instruction pointer, possibly because it has been optimized away. System.Threading.Tasks.TaskExceptionHolder

How can I troubleshoot this problem?

I also found this question which is pretty similar.

Answer 1

As the message says, you have a task which threw an unhandled exception.

Turn on Break on All Exceptions (Debug, Exceptions) and rerun the program.
This will show you the original exception when it was thrown in the first place.

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(comment appended): In VS2015 (or above). Select Debug > Options > Debugging > General and unselect the "Enable Just My Code" option.