how can I fix Value cannot be null. Parameter name: format error in window forms design appearing after renaming project folder

Question

Answer 1

Hello @Wil-G ,

Welcome to Microsoft Q&A forum.

After you renamed your project folder, did you also check and rename/change the class name/the code behind the file?

Probably, there are some unchanged names/code in your solution, please kindly double check it.

Sincerely,

Tianyu

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