Visual Studio.Net – Build Error – “Error CS0229 Ambiguity between …”


Experiencing error building a project in Visual Studio.


Error Image


Error Message

  1. Error CS0229 Ambiguity between ‘_jobSummary’ and ‘_jobSummary’
  2. Error CS0121 The call is ambiguous between the following methods or properties: ‘ExecJobActionAsync(Func<DbConnection, Task<int>>)’ and ‘ExecJobActionAsync(Func<DbConnection, Task<int>>)’
  3. Error CS0229 Ambiguity between ‘IsEnabled’ and ‘IsEnabled’
  4. Error CS0229 Ambiguity between ‘IsRunning’ and ‘IsRunning’



After a full day’s work, realized that the source of the problem is that I had backed up one of the source code files before editing it.

Unfortunately, the backup file was placed in a folder underneath the project’s working directory.


To correct please do one of the following :-

  1. Move the folders and files outside of the project’s working directory
  2. Explicitly exclude the folder or file from the project


Visual Studio .Net Project


  1. Choose the folders or files to exclude
    • Right click on your selection
    • From the drop-down menu, please choose Exclude


Image – Exclude From Project ( Initiate )


Image – Exclude From Project ( Completed )




To review included and excluded files you can do the following :-


  1. Ensure that Solution Explorer is tailored to show all files
  2. Review each .csproj file



Solution Explorer

Image – Show All Files


Project File ( .CSProj )



  1. Upon reviewing the .csproj file we notice the following
    • A new ItemGroup
    • The Item is tagged with “Compile Remove



Please be careful where you place copied files as it might inadvertently be included in your project.

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