You may encounter a serious error when opening a Revit project, certain views or reloading a link when the linked files in the project have errors that prevent file to be opened, or when Revit is not updated to the latest version.
Make sure that Revit has the latest update and hotfix installed: https://www.autodesk.com/support/download-install/individuals/manage/update-your-software.
Open the model with an Audit
Review and handle any warnings in the model
If none of the above helps, reinstall Revit.