Demo project for EF Core issue 34749.
Update the sql server connection string in appsettings.json.
Run the application. The database will automatically be created and filled with test data.
To reproduce the error choose GET Locations and Try Out. Don't enter a language in the query parameter. Just choose Executein Swagger UI.
(If you enter a language, i.e. "de" or "en" you can check issue 34752.)
The LINQ for the query can be found at VC.WebApi/Features/Locations/GetLocations/GetLocationsRepository.cs
The created SQL query has an extra faulty 2nd LEFT JOIN and doubled fields in the SELECT:
SELECT [l].[LocationId], [l].[Name], [t].[ImageId], [t].[DisplayOrder], [t].[Language], [t].[ScreenSize], [t].[FocusPointX], [t].[FocusPointY], [t].[Uri], [t].[c], [t].[c0], [t].[TId], [t].[ImageId0], [l].[Created], [l].[CreatedBy], [l].[CreatedInNameOf], [l].[LastModified], [l].[LastModifiedBy], [l].[LastModifiedInNameOf], [l].[TId], [l].[Version], [l].[Address_City], [l].[Address_CountryId], [l].[Address_CountryName], [l].[Address_DeliveryInstruction], [l].[Address_State], [l].[Address_Street], [l].[Address_StreetAffix], [l].[Address_StreetNumber], [l].[Address_ZipCode], [l1].[TId], [l1].[DisplayOrder], [l1].[FocusPointX], [l1].[FocusPointY], [l1].[ImageId], [l1].[Language], [l1].[LocationId], [l1].[ScreenSize]
FROM [VC].[Location] AS [l]
LEFT JOIN (
SELECT [l0].[ImageId], [l0].[DisplayOrder], [l0].[Language], [l0].[ScreenSize], [l0].[FocusPointX], [l0].[FocusPointY], [i].[Uri], CAST([i].[MetaData_Width] AS bigint) AS [c], CAST([i].[MetaData_Height] AS bigint) AS [c0], [l0].[TId], [i].[ImageId] AS [ImageId0], [l0].[LocationId]
FROM [VC].[LocationCoverImage] AS [l0]
INNER JOIN [VC].[Image] AS [i] ON [l0].[ImageId] = [i].[ImageId]
) AS [t] ON [l].[LocationId] = [t].[LocationId]
LEFT JOIN [VC].[LocationCoverImage] AS [l1] ON [l].[LocationId] = [l1].[LocationId]
ORDER BY [l].[LocationId], [t].[TId], [t].[ImageId0]