error C1859: 'Debug\Foo.pchast' unexpected precompiled header error, simply rerunning the compiler might fix this problem - by Roger Lipscombe

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ID 524418 Comments
Status Active Workarounds
Type Bug Repros 10
Opened 1/12/2010 3:19:59 AM
Access Restriction Public


When attempting to compile a C++ solution, I receive this error, for multiple PCHAST files in my project. Rerunning the compiler does not fix the problem. Deleting the PCH and PCHAST files and rerunning the compiler also does not fix the problem.

Turning off /analyze is not a workable solution, long term.

This looks a bit like the issue discussed here:, except that:

I'm on Windows 2008 (i.e. Vista), rather than Windows 7.
This is the PCHAST files (i.e. the output from /analyze) rather than the PCH files.

The linked blog entry says "This fix will be available in the final release of Visual Studio 2010", but doesn't talk about PCHAST files; nor does it say explicitly that this bug exists in beta2. Also I'm on Windows 2008, not Win7.
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Posted by Daniel D'Cotta on 7/8/2012 at 8:58 PM
Thank you, Roger Lipscombe for the workaround.

I encountered this same error and a reboot solve it.
Posted by Alex V. Ivanoff on 5/12/2010 at 12:15 PM
Not fixed in RTM.
Posted by Reza Bemanian on 2/20/2010 at 3:03 PM

I am using VS2010 RC1, and trying to compile a VS2008 solution results in generation of numerous C1850 fatal error codes for the precompiled header units. Is this problem has been resolved for the RC1?

Best Regards,

Alireza Bemanian, PhD
Posted by Microsoft on 1/14/2010 at 5:30 PM
Thank you for your feedback. You are correct the problem you are encountering is the one described in the blog post you link, dealing with rebasing PCH's. As the blog post notes, we have fixed this issue and the fix will appear in the final version of VS2010. This issue was not fixed in time to make it into Beta2, however.

I can confirm that experiencing this issue with VS2010 on Windows Server 2008 is not entirely unexpected. I can also confirm that the issue is the same with PCHAST files and that our fix, when available, will apply to those as well as PCH files. In short, you should see everything working right in the final release of VS2010.

-Brett Wortzman
Visual Studio Code Analysis Team
Posted by Microsoft on 1/13/2010 at 7:01 PM
Thanks for your feedback.

We are routing this issue to the appropriate group within the Visual Studio Product Team for triage and resolution.
These specialized experts will follow-up with your issue.
Posted by Roger Lipscombe on 1/13/2010 at 1:41 AM
Rebooting (as suggested in the comments to the blog entry) fixes it. I'm just looking for confirmation that the PCHAST file problem is the same as the PCH problem mentioned in the blog, and that it's also been fixed.
Posted by Microsoft on 1/13/2010 at 1:15 AM
Thanks for reporting the issue.
In order to fix the issue, we must first reproduce the issue in our labs. We are unable to reproduce the issue with the steps you provided.

Could you please attach a zipped project file to this feedback through our site to help us reproduce the issue?

Thanks again for your efforts and we look forward to hearing from you.
Visual Studio Product Team