Unable to cast object of type 'System.Web.SessionState.SessionStateItemCollection' to type 'Microsoft.Web.Redis.ChangeTrackingSessionStateItemCollection'.

[footcha]

Hello,
last week we started using Microsoft.Web.RedisSessionStateProvider in our live environments globally. Since then we are experiecing tens of millions exceptions per day (a log bellow is exported from Application Insights):

[{
    "severityLevel": "Critical",
    "outerId": "57776361",
    "message": "Unable to cast object of type 'System.Web.SessionState.SessionStateItemCollection' to type 'Microsoft.Web.Redis.ChangeTrackingSessionStateItemCollection'.",
    "parsedStack": [{
        "assembly": "Microsoft.Web.RedisSessionStateProvider, Version=3.0.2.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35",
        "method": "Microsoft.Web.Redis.RedisConnectionWrapper.SetPrepare",
        "level": 0,
        "line": 0
    },
    {
        "assembly": "Microsoft.Web.RedisSessionStateProvider, Version=3.0.2.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35",
        "method": "Microsoft.Web.Redis.RedisConnectionWrapper.Set",
        "level": 1,
        "line": 0
    },
    {
        "assembly": "Microsoft.Web.RedisSessionStateProvider, Version=3.0.2.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35",
        "method": "Microsoft.Web.Redis.RedisSessionStateProvider+<SetAndReleaseItemExclusiveAsync>d__25.MoveNext",
        "level": 2,
        "line": 0
    }],
    "type": "System.InvalidCastException",
    "id": "12895194"
}]

After two days of investigations I still cannot say preciselly which part of ASP.Net pipeline is responsible for passing object of type SessionStateItemCollection into a method RedisSessionStateProvider.SetAndReleaseItemExclusiveAsync.

It seems that despite such a huge number of exceptions it does not have remarkable negative impact on user experience. Still, this issue makes me worried a lot.

I will prepare a pull request to eliminate such errors.

[footcha]

Is there any progress in reviewing the related pul request and this issue itself?