Migration
From 4.X to 5.X
The biggest requirement will be to migrate to dotnet 6. See Migrate from ASP.NET Core 5.0 to 6.0
After completing that dotnet 6 migration the blazor-state specific changes are as follows:
Remove the script tag in your index.html or _Host.cshtml files
Delete:
<script src="_content/BlazorState.js/blazorstate.js"></script>