Interesting question!!! nothing is foolish as long we show interest to learn new things.
Coming to your question, we need to follow certain rules in the SharePoint migration project whether it is on-premise to on-premise migration or SharePoint online migration.
Prepare the below checklist :
- Get the source site structure inventory it might have a lot of nested subsites.
- In modern SharePoint online subsites are not recommended - Microsoft recommends to have each site as separate site collection (here we don't call as site collection, we call as a site).
- Prepare a mapping excel which source site goes to which target the modern site. Including each subsite to a modern SharePoint online site.
- Create an inventory about all list or library in source site which has more than 5k items because for threshold issue need to take special care post-migration.
- Create an inventory about all checked out files in source site because during migration will get error for this.
- Create an inventory about all lookup lists in the source.
- Make sure while migrating the list, you migrate the parent lookup list then then the main list.
- Create an inventory about all workflows in the source, categorize like which are designer workflow or Nintex workflow or any other workflow.
- Make sure before migration user completes all running workflow in the source.
- Create an inventory about all InfoPath forms in the source and come up with a plan to develop an alternate form for those because after 2023 Microsoft will support InfoPath form.
- If you custom WSP solution, prepare an alternate plan to redevelop the solution using modern technology like SPFx framework, custom WSP cannot be migrated to SharePoint Online.
- Prepare an inventory about all long file path in the source, and create an mapping excel what should be the shorten path after the migration.
- Create an inventory about supported file types in source and target, so that if some files do not get migrated, you will know the reason.
- There will be a chance that you will not get all users in the target SharePoint online, so create a dedicated migration user which will be mapped for missing users, otherwise for missing user logged in user will be used which is not recommended.
- Try to use any of third party tools like ShareGate or Metalogix.
- Don't do the content and structure migration together.
- First do the structure migration then go for content migration.
- For content migration don't do all site content together, go list by list migration otherwise error handling will be messed up.
- Make sure you set list default experience to modern in target before migration, it can be done through the tool.
- Make sure you lock down the source site during migration otherwise you need have proper delta or incremental migration plan.
- Prepare a plan for hub site and Megamenu structure in SharePoint online and connect each migrated site to the specific hub site.
- Prepare an end-user training plan because UI will be completely changed after migration.
- Identify a dedicated site owner for each migrated site and do not plan more than two site owners for single-site otherwise it will be messed.
- After each site migration, get the confirmation from the responsible site owner then mark the site migration status as done.
- After migration randomly navigates through site navigation mainly the InfoPath form and user permissions in the site.
- Last but not the least, don’t forget to have a rollback plan for any type of uncertainty and Plan B for the migration – these two are very important.
As of now, I can remember these, if anything I remember, I will update it.
In the migration project, planning is the key aspect, the better you plan more you will get success.
Most of the inventory report we can get from migration tool like sharegate and Metalogix.
For details refer to the below article:
25 quick checklists for SharePoint migration