Hi, thank you for using the Prime Mover plugin! Below are simple rules on how plugins/themes are handled during migration. Take note these only apply when you migrate using complete export (that includes plugins /themes on it)
- Prime Mover will copy the plugin from the source package to the target site. E.g. If the source site has Plugin A and the target site has Plugin A as well. Then Prime Mover will delete Plugin A at target site and replace it with Plugin A from the source site package.
- Prime Mover will copy theme from the source package to target site. E.g. If source site has Theme Z and target site has Theme Z as well. Then Prime Mover will delete Theme Z in target site first and then replace it with Theme Z from source site package.
- The other plugins/themes in the plugins/themes directory that are not part of the migration package are untouched (not deleted, overwritten or edited in any way). For example if package only has Plugin A, B and C. And target site has existing Plugin A, B, C, D and E. Prime Mover will not delete or overwrite plugin D and E.
The above rules are applied regardless if you are migrating from single-site to single site, single-site to multisite, multisite to multisite, multisite to single-site. The above rules ensure that the package are migrated correctly to target site. Since plugins / themes are included in the package (if it’s complete package you are restoring) – they are dependencies of the source site to work correctly.
So to answer your questions:
- What happens during migration? Are theme X, theme Z, plugin A, plugin B overwritten in multisite?
Answer: What happens during migration (following the above rules) – is that if plugins exists in target multisite, it will be replaced or overwritten with the plugins /themes from the package.
- Or will Prime Mover skip preexisting plugins/themes leaving them untouched?
Answer: Target site plugins/themes are untouched only if you are migrating a package that does not include plugins/themes on it (e.g. DB only package or DB + Media package type). In this case – Prime Mover will do a compatibility check before import and warn if you want to proceed migrating just in case the plugin/theme versions are different from the source and target site. This is important if your source site is not tested to work with the target site plugin /theme versions.
But if you are migrating a complete exported package – Prime Mover will eventually replace plugins / themes in the destination site.
- Would we need to manually transfer each new theme/plugin (a delicate as well as tedious task), just export the database from the single site and then go through the whole process again every time we need to import a new single site as sub-site?
Answer: It depends on your case and convenience. For example – if all of your plugin/theme versions are the same for both source single site and target multisite. Then it would be best to just migrate the database/media files if all needed plugins /themes exists in target multisite and running the same versions. Target multisite plugins/themes are untouched in this case.
But if versions are different or if some plugins/themes in single site are not found in the multisite – then migrating using complete package is nice since it will surely copy all plugins /themes needed from the source site to target site. This way there is no tedious work of copying each plugins/themes manually.
If you have complex sites – you must test them first entirely in a local or development server before rolling out the migrating work to production or live site. By testing locally / developing, you know exactly if the migration will be compatible with your target multisite.
Thank you again for your question and if you have further questions – please check out this related question from another user in our FAQ.