How fix Solution when have been added website from filesystem without project file

Conversion tool migration aborted.

When migrating a webforms solution it is possible to experience an error related to a project with an invalid empty extension.

When this error happened?

This happens when a website is added to a solution from a filesystem directory.

Step 1: Select add website

Step 2: Select the directory from filesystem

Step 3: WebSite is added to solution

How to Fix?

Step 1: Remove the existing website from solution

Step 2: Add new project (This will be used as a template for the existing website)

Step 3: Select new Web Application

Step 4: Configure the project with a different name of the existing folder with the website files in it.

Step 5: Create the WebForms project

Step 6: Rename the created project with original website name

Step 7: Remove the project from the solution.

Step 8: Copy the generated csproj file to the original website directory

Step 10: Add the existing project in the original website directory to the solution

Step 11: Select option in solution explorer Show all Files

Step 12: Include the files to the project and exclude the ones that are not going to be part

Step 13: Add the needed references to the project. (Can use as reference the ones in the solution file, that exist for the original website)

Step 14: Compile and try to migrate