Upon one-click publish: Exception in executing publishing: An item with the same key has already been added

Question

I realize that a billion people have asked about this error, but I\'ve looked at all of them. Mine seems different. I\'m not getting any sort of source code error, no stack trac

Answer 1

While @Andrew's method is the correct approach, I find it faster to just delete the offending publish profile and reinstall / create a new one. I keep my publish profile in the same place so it takes about 10 seconds to re-install.

Answer 2

I was wrong about there not being any changes to the publishing profile. Here is what happened.

I set up a code-first Entities context called, say, MyDBContext. In my publishing profile myprofile.pubxml, Some code automatically gets inserted like this:

<PublishDatabaseSettings>
  <Objects xmlns="">
    <ObjectGroup Name="MyDBContext" ......
<MSDeployParameterValue Include="$(DeployParameterPrefix)MyDBContext-Web.config Connection String" />

Then, I decide to try the EDMX stuff. But I save my old structure just in case. Now the File looks like this:

<PublishDatabaseSettings>
  <Objects xmlns="">
    <ObjectGroup Name="MyDBContext" Order="1" ......
    <ObjectGroup Name="myEntities" Order="2" ......
<MSDeployParameterValue Include="$(DeployParameterPrefix)MyDBContext-Web.config Connection String" />
<MSDeployParameterValue Include="$(DeployParameterPrefix)myEntities-Web.config Connection String" />

But then, I decide to ditch the EDMX stuff. Somehow, though, instead of removing the second set of entries in the .pubxml file, this happened:

<PublishDatabaseSettings>
  <Objects xmlns="">
    <ObjectGroup Name="MyDBContext" Order="1" ......
    <ObjectGroup Name="MyDBContext" Order="2" ......
<MSDeployParameterValue Include="$(DeployParameterPrefix)MyDBContext-Web.config Connection String" />
<MSDeployParameterValue Include="$(DeployParameterPrefix)MyDBContext-Web.config Connection String" />

Voila. Second set removed, and I'm good to go.

Answer 3

instead of deleting, go inside properties/PublishProfiles, open the .pubxml file and check to see if your connection strings have been repeated/duplicated. I had this issue, removed all the duplicate connection strings to leave one remaining and it solved my issue.

Answer 4

I got this error. It turns out there was a binding error with the solution file. Had to delete the publishing files and bind the solution. Then I could use the Publish button again.