Keyword not supported: "data source" initializing Entity Framework Context

This appears to be missing the providerName="System.Data.EntityClient" bit. Sure you got the whole thing?

The real reason you were getting this error is because of the " values in your connection string.

If you replace those with single quotes then it will work fine.

https://docs.microsoft.com/archive/blogs/rickandy/explicit-connection-string-for-ef

(Posted so others can get the fix faster than I did.)

I fixed this by changing EntityClient back to SqlClient, even though I was using Entity Framework.

So my complete connection string was in the format:

<add name="DefaultConnection" connectionString="Data Source=localhost;Initial Catalog=xxx;Persist Security Info=True;User ID=xxx;Password=xxx" providerName="System.Data.SqlClient" />