System.NullReferenceException when downloading error log in csv format

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System.NullReferenceException when downloading error log in csv format

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Original comment by azizatif on 3 Nov 2007 at 12:36

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Original comment by azizatif on 4 Nov 2007 at 2:56

• Changed state: Accepted

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Original comment by azizatif on 4 Nov 2007 at 2:57

• Added labels: Component-Logic

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This was a tough cookie, but fixed in r236. The problem occurred due to 
synchronous 
completion of an asynchronous operation. More specifically, 
ErrorLogDownloadHandler.BeginProcessRequest could return a null IAsyncResult if 
the 
downstream ErrorLog.BeginGetErrors operation completed synchronously. The 
problem 
was solved by copying a reference of the IAsyncResult object on the stack from 
within ErrorLogDownloadHandler.BeginProcessRequest.

Original comment by azizatif on 4 Nov 2007 at 3:00

• Changed state: Fixed

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So was I almost right? ;) Actually, making _result null removed the only 
reference to
that object.

Original comment by [email protected] on 4 Nov 2007 at 10:46

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Almost, right. :) Removing the _result reference as you suggested would have 
helped 
this once case but it would have been logically not the right solution and 
therefore 
probably caused another bug somewhere down the road. However, given the fix I 
made, 
I can now see how what you were suggesting seemed to make things look alright. 
Also, 
it explains why it always occurred in 1.x but only seldom in 2.0. The 
SqlErrorLog is 
always synchronous under 1.x but synchronous/asynchronous under 2.0. The bug 
was 
with synchronous completion of asynchronous requests and that could happen from 
time 
to time.

Original comment by azizatif on 4 Nov 2007 at 11:38