Home → Support →

Build error: An error occurred while compiling the views

• Edit

chrispeoples

Sep 20, 2016 @ 07:14 PM

You guys must be tired of hearing from me now, but I ran into another issue. A few days ago I updated my project to .NET 4.5.1 and MVC 5.2.3. It was building fine until today, when new changes I deployed caused the build to fail. The error says:

(0): error CS1705: Assembly 'PickemApp, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null' uses 'System.Web.Mvc, Version=5.2.3.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' which has a higher version than referenced assembly 'System.Web.Mvc, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35'

However, I can't find anywhere in my project that references System.Web.Mvc, Version=1.0.0.0. And as I said, I made the upgrade on 2016-09-16, and all builds between then and now worked fine.

Any ideas why this isn't working now? Thanks so much for your help.

1. Support Staff 1 Posted by rune on Sep 21, 2016 @ 10:40 AM

   

   Hi,

   Not quite sure what's happening here, but I suspect it's related to a missing compilation section in your view web.config -- the System.Web.Mvc namespace is added in your views' web.config, but the assemble doesn't seem to be specified for compilatiion. Try and add that section and push the app again (here's an example using a standard VS2015 MVC template app).

   Best,
   Rune

   • Edit

2. 2 Posted by chrispeoples on Sep 21, 2016 @ 04:39 PM

   

   That seemed to work, but only when I had precompilation turned off. Once I
   reenabled precompilation, it failed again. Could there be some remnants of
   an old System.Web.Mvc.dll in the build folder?

   • Edit

3. Support Staff 3 Posted by rune on Sep 23, 2016 @ 11:12 AM

   

   Hi,

   At least not on the AppHarbor build servers at -- but it's likely that there are still dependencies on your own machine that causes the build to succeed locally but fail on AppHarbor. Have you tried cleaning your repository to verify this? Executing git clean -fdx will clean the repository and delete any untracked files and unstaged changes. This can be quite efficient for isolating this type of dependency related issues (except the System.Web.Mvc dependency in this case is likely installed in the GAC, so you might want to uninstall MVC from your machine if that's the case).

   On a related note, disabling precompilation doesn't really solve the underlying the issue - it just removes that step and pushes the error to the runtime environment, which is one of things precompilation helps reduce the risk of.

   Best,
   Rune

   • Edit

4. 4 Posted by chrispeoples on Sep 23, 2016 @ 05:20 PM

   

   I figured it out. I had added an App_Code folder in order to use a global
   Razor helper. Apparently MVC5 does not like the App_Code folder. I removed
   it and it's building again.

   Thanks for your help.

   -Chris

   • Edit

5. Support Staff 5 Posted by rune on Sep 24, 2016 @ 03:17 PM

   

   Hi Chris,

   Ok good to hear you figured it out!

   Best,
   Rune

   • Edit

6. rune closed this discussion on Sep 24, 2016 @ 03:17 PM.