For security we've recently created a new database user with tightened up permissions for usual access (https://en.wikipedia.org/wiki/Principle_of_least_privilege), the user doesn't need to be a superuser or have any alter table permissions. Due to soft-deleting being common it shouldn't need Delete permission for most tables either.
The Volo.Abp.OpenIddict.Tokens.OpenIddictToken class is setup as a FullAuditedAggregateRoot which has soft-deleting enabled but it's not actually using it so when we revoked the delete permissions the system stopped working properly.
Quick fix is to re-grant the Delete permission, but the OpenIddictToken class should either be setup to use soft-deleting as its inheritance provides, or its inheritance should be changed so we don't have unnecessary unused columns present on the database table.
Your provided link to "Migrating to Blazor Web App" is broken and linking back to this post.
We're also in the process of upgrading to 8.2 and I came across the same issue and the lack of 8.2 guides.
For our localization configuration inside Configure<AbpLocalizationOptions> the FlagIcon parameter in the LanguageInfo constructor was identical to the CultureName parameter so I've just removed the parameter for now as I'm not sure we're actually using the FlagIcon itself anywhere so we'll see if that causes any problems.
Also had the same issue with the new IdentitySession inside our DbContext but solved that by adding a reference to the new Sessions table as required by the IIdentityProDbContext interface. public DbSet<IdentitySession> Sessions { get; set; }