How do I upgrade from OSLion to catalina

Back up your data, check the application compatibility table, click here, then on the download link for an intermediate OS, and then it. If you're using a Mac Pro as listed below your post, you can't; none of these supports both Lion and Catalina.

Catalina and higher won't run 32-bit software; if you upgrade to one of them, use Go64 as well.

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