ABP Upgrade Checklist: from any version to ABP 10

Before you start

Record the current ABP, SDK, EF Core and front-end (Angular, Blazor or MVC) versions.
List every ABP module in use, open source and commercial, and check your license covers the target version.
List every ABP service, page or component you have overridden or replaced.
List third-party packages that depend on a specific runtime or ABP version.
Make sure the build is green and the main user flows have tests or a written test script.
Back up production data and agree a rollback plan.

Choose the target version. For most teams today this is ABP 10.
Read ABP's migration guide for every major version between your current and target versions.
Plan one major version per step, each on its own branch with its own staging release.
If you are below ABP 6, plan the move from IdentityServer to OpenIddict as a separate task.
Estimate each step after reading the guides, not before.

Update the ABP CLI or ABP Studio to the matching version.
Update all Volo.Abp NuGet packages and @abp npm packages to the same version.
Update the target framework and SDK version in global.json and the build pipeline.
Fix compile errors and replace obsolete APIs flagged by the compiler.
Add an EF Core migration, review it line by line, and apply it to a copy of production data.
Update the front end: Angular versions via ng update, or Blazor and MVC packages.
Run all tests, then smoke-test the checks in the next section.
Release to staging and let the team use it before moving to the next version.

Map each IdentityServer client to an OpenIddict application with the same redirect URLs.
Map API scopes and resources, and check token lifetimes.
Update signing and encryption certificates for production.
Re-test every client: SPA, mobile app, server-to-server and Swagger.