Local IIS 7.0 - CS0016: Could not write to output file / Microsoft.Net > Framework > v4.0.30319 > Temporary ASP.NET Files

Solution to an annoying error message! You are getting 'Could not write to output file 'c:\Windows\Microsoft.NET\Framework\....' message? You are at the right place.
5 March 2011
2 minutes read

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This week I went nuts over my local IIS. I have never swore to a machine that much in my whole life. I am sure of that! The problem is not that big and probably not worth to be written on a blog post I am going to write it anyway because the solution was hard to find on the internet. Maybe this post will help you to fix the problem as I did and you will stop swearing to you machine as I did Smile

Let’s get to the point. I am no IIS guy! Seriously!  The so called Cassini (the tiny web server which pops up when you run a web application on Visual Studio) was so enough for me for over 2 years. But no more enough. I figured that IIS can not be ignored by me anymore. How can I get that point? That’s not the issue here. The issue is that I tried to run an ASP.NET MVC 3.0 application under my local IIS 7.0 and got a very annoying error. Which is;

Compiler Error Message: CS0016: Could not write to output file 'c:\Windows\Microsoft.NET\Framework\v4.0.30319\Temporary ASP.NET Files\root\62d43c41\27d749ca\App_Code.7lodcznm.dll' – 'Access denied.'

imageTemporary ASP.NET Files folder (c:\Windows\Microsoft.NET\Framework\v4.0.30319\Temporary ASP.NET Files) was the the one with the problem here. First, I thought that the problem is related to security permissions on the folder and I was right.

I right clicked on the Temporary ASP.NET Files folder and go to the security tab. I noticed that there is user called IIS_IUSRS and that guy has the full control permission. But apparently that was not enough.

The Temporary ASP.NET Files  and C:\Windows\temp folders should have IIS_WPG and NETWORK SERVICE users with the full control permission. I have no idea why C:\Windows\temp folder needs that but I have no effort left to try to find that. Instead, I am writing a blog post about the problem. Maybe latter I will get to that and figure it out, too Smile

Once you applied those setting, restart your IIS and try to run your application again. The error should be gone by now.

I suffered a lot by trying to find the right method for the problem and I hope you didn’t have to go through hell over this.

Hope this helps Smile