catch block not catching exception in another thread

Question

method A()
{
  try
  {
    Thread t = new Thread(new ThreadStart(B));
    t.Start();
  }
  catch(exception e)
  {
    //show message of exception
  }      

}

method B()
{
 // getDBQuery
}

a exception in B but not catched. does it legal in .net?

See answer to [this question](http://stackoverflow.com/q/5983779/395718) for ways to get exception from another thread. — Dialecticus, Nov 04 '13 at 15:34

H H · Answer 1 · 2013-11-04T15:03:26.727

7

Correct, exceptions from a Thread are not forwarded to the caller, the Thread should handle this by itself.

The most general answer is that you should not be using a (bare) Thread here. It's not efficient and not convenient.

When you use a Task, the exception is stored and raised when you cal Wait() or Result.

edited Nov 04 '13 at 15:03

answered Nov 04 '13 at 14:59

H H

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score 4 · Accepted Answer · answered Nov 04 '13 at 14:59

When A is finished executing B might still be running as it is on an independent thread. For that reason it is impossible by principle for A to catch all exceptions that B produces.

Move the try-catch to inside of B. The Thread class does not forward exceptions.

Better yet, use Task which allows you to propagate and inspect exceptions.

catch block not catching exception in another thread

2 Answers2