You'll need to first upgrade to beta.5 and then upgrade to beta.6. The reason why this doesn't work has very little to do with beta.6. The root cause is the catalog migrations which add admin metadata using yaml files (an RQL query); these RQL queries require schema cache to run but building schema cache could fail because the function which does this assumes the latest catalog's schema.

The conclusion is that we can't use RQL queries in catalog migrations and we'll need to rewrite these migrations using only SQL.

This happened earlier too in one of the alpha versions.