I created a new mod, added the first elements and got the following error message when exporting: (see screenshot) then I deleted the mod and made everything again the same error message
MCreator issue tracker has been migrated to GitHub.
Existing tickets have been migrated to GitHub. Please open new tickets on the GitHub tracker instead. If you do not have a GitHub account, all feature requests and bug reports from forums are still considered and checked by the maintainers.