When I click edit on a post, all the content disappear. Does anyone know how to fix this?

Something went wrong with your migration. A plugin– I think it is this one— does not have the table(s) it needs to operate. I assume that some tables were not transfered. Disable that plugin, then reactivate it and this should clear up. I assume that the plugin will create its tables on re-activation.

If you can’t get to the backend to disable it, just delete it or rename the directory, then reinstall it.