Coveo 7: Custom Control Errors

A few weeks ago I embarked on my second Coveo implementation. This was to be my first using Coveo 7 and the out-of-the-box controls that come packaged with the Coveo .NET Front End. My previous implementation utilized Coveo 6.5 and the Coveo Web Service.

After following Coveo’s fairly simple instructions found in their online help section:, I created a custom control but immediately ran into the follow error:

Coveo Custom Controls Error

Coveo Custom Controls Error

As it turns out, the Visual Studio project included in the Coveo .Net Front End v12.0 installer reference Coveo v6 DLLs. Because I also have a version of Coveo v6.5 installed alongside Coveo v7, I received the above error. Had I not had a Coveo v6.5 install, I would have seen an error message of:

Parser Error Message: Unable to create type ‘coveo:CustomResultField’. Could not load file or assembly ‘Coveo.CES.Web.Search, Version=, Culture=neutral, PublicKeyToken=44110d16825221f2’ or one of its dependencies. The system cannot find the file specified.”

The fix is simple. Update the project’s references to Coveo DLLs to point to their 12.0 versions. The DLLs whose references need updating are:

  • Coveo.Web.Search.dll
  • Coveo.CNL.dll
  • Coveo.CNL.Web.dll

These DLLs can be found in the GAC or the Bin folder within the root of the Coveo .NET Front End install directory.

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