Hi @Sandy Gordon,
Welcome to Microsoft Q&A!
What is your project type and the version of Visual Studio? Could you create a new project and check if it occurs in specific project?
You can try the following workarounds:
- Update your VS to the latest version.
- Repair your VS with Visual Studio Installer > More > Repair.
- Check the target framework.
- Check that the project's references load properly.
- Close all running VS instances and delete the hidden .vs, bin and obj folders in the project folder. Then, clean and rebuild the solution.
Sincerely,
Anna
If the answer is the right solution, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment". Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.