SOLVED: API Error processing requests for /emby/Sessions

[kattolo]

I am running Jellyfin 10.10.6 in a docker container, on Debian12 on RaspberryPi 5

I have a self hosted gethomepage in another docker container that has Jellyfin as one of the services, and uses a native plugin to connect to my local Jellyfin server; it retrieves the necessary information, and presents them in the homepage (for example number of hosted movies, episodes, songs, and in case some user is viewing a movie details on what is being played)

Up until a couple of days ago it was working properly, but after an OS update/upgrade and reboot, it is showing an API error instead of the Jellyfin information

Code:

API Error: HTTP Error
URL: http://mylocal.domain:8096/emby/Sessions?api_key=***
Response Data:
"Error processing request."

I attempted to connect via browser to other Jellyfin API URLs with different API keys and they all work properly, but all iterations of  http://mylocal.domain:8096/emby/Sessions?api_key=*** fail with an Error processing request

The Jellyfin logs around the  timestamp of my attempts from browser are perfect matches to the many more instances of the same errors in the logs (supposedly the gethomepage Jellyfin Plugin attempts):

Code:

[2025-03-17 00:09:41.865 +00:00] [ERR] [28] Jellyfin.Api.Middleware.ExceptionMiddleware: Error processing request. URL "GET" "/Sessions".
System.InvalidCastException: Unable to cast object of type '<>z__ReadOnlyArray`1[MediaBrowser.Model.Session.GeneralCommandType]' to type 'MediaBrowser.Model.Session.GeneralCommandType[]'.
  at System.Text.Json.JsonSerializer.UnboxOnWrite[T](Object value)
  at System.Text.Json.Serialization.JsonConverter`1.WriteAsObject(Utf8JsonWriter writer, Object value, JsonSerializerOptions options)
  at System.Text.Json.Serialization.JsonConverter`1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
  at System.Text.Json.Serialization.Metadata.JsonPropertyInfo`1.GetMemberAndWriteJson(Object obj, WriteStack& state, Utf8JsonWriter writer)
  at System.Text.Json.Serialization.Converters.ObjectDefaultConverter`1.OnTryWrite(Utf8JsonWriter writer, T value, JsonSerializerOptions options, WriteStack& state)
  at System.Text.Json.Serialization.JsonConverter`1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
  at System.Text.Json.Serialization.Metadata.JsonPropertyInfo`1.GetMemberAndWriteJson(Object obj, WriteStack& state, Utf8JsonWriter writer)
  at System.Text.Json.Serialization.Converters.ObjectDefaultConverter`1.OnTryWrite(Utf8JsonWriter writer, T value, JsonSerializerOptions options, WriteStack& state)
  at System.Text.Json.Serialization.JsonConverter`1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
  at System.Text.Json.Serialization.Converters.ListOfTConverter`2.OnWriteResume(Utf8JsonWriter writer, TCollection value, JsonSerializerOptions options, WriteStack& state)
  at System.Text.Json.Serialization.JsonCollectionConverter`2.OnTryWrite(Utf8JsonWriter writer, TCollection value, JsonSerializerOptions options, WriteStack& state)
  at System.Text.Json.Serialization.JsonConverter`1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
  at System.Text.Json.Serialization.JsonConverter`1.WriteCore(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
  at System.Text.Json.Serialization.Metadata.JsonTypeInfo`1.SerializeAsync(Stream utf8Json, T rootValue, CancellationToken cancellationToken, Object rootValueBoxed)
  at System.Text.Json.Serialization.Metadata.JsonTypeInfo`1.SerializeAsync(Stream utf8Json, T rootValue, CancellationToken cancellationToken, Object rootValueBoxed)
  at System.Text.Json.Serialization.Metadata.JsonTypeInfo`1.SerializeAsync(Stream utf8Json, T rootValue, CancellationToken cancellationToken, Object rootValueBoxed)
  at Microsoft.AspNetCore.Mvc.Formatters.SystemTextJsonOutputFormatter.WriteResponseBodyAsync(OutputFormatterWriteContext context, Encoding selectedEncoding)
  at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeNextResultFilterAsync>g__Awaited|30_0[TFilter,TFilterAsync](ResourceInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
  at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Rethrow(ResultExecutedContextSealed context)
  at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.ResultNext[TFilter,TFilterAsync](State& next, Scope& scope, Object& state, Boolean& isCompleted)
  at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.InvokeResultFilters()
--- End of stack trace from previous location ---
  at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeNextResourceFilter>g__Awaited|25_0(ResourceInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
  at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Rethrow(ResourceExecutedContextSealed context)
  at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
  at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.InvokeFilterPipelineAsync()
--- End of stack trace from previous location ---
  at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeAsync>g__Awaited|17_0(ResourceInvoker invoker, Task task, IDisposable scope)
  at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeAsync>g__Awaited|17_0(ResourceInvoker invoker, Task task, IDisposable scope)
  at Jellyfin.Api.Middleware.ServerStartupMessageMiddleware.Invoke(HttpContext httpContext, IServerApplicationHost serverApplicationHost, ILocalizationManager localizationManager)
  at Jellyfin.Api.Middleware.WebSocketHandlerMiddleware.Invoke(HttpContext httpContext, IWebSocketManager webSocketManager)
  at Jellyfin.Api.Middleware.IPBasedAccessValidationMiddleware.Invoke(HttpContext httpContext, INetworkManager networkManager)
  at Jellyfin.Api.Middleware.LanFilteringMiddleware.Invoke(HttpContext httpContext, INetworkManager networkManager, IServerConfigurationManager serverConfigurationManager)
  at Microsoft.AspNetCore.Authorization.AuthorizationMiddleware.Invoke(HttpContext context)
  at Jellyfin.Api.Middleware.QueryStringDecodingMiddleware.Invoke(HttpContext httpContext)
  at Swashbuckle.AspNetCore.ReDoc.ReDocMiddleware.Invoke(HttpContext httpContext)
  at Swashbuckle.AspNetCore.SwaggerUI.SwaggerUIMiddleware.Invoke(HttpContext httpContext)
  at Swashbuckle.AspNetCore.Swagger.SwaggerMiddleware.Invoke(HttpContext httpContext, ISwaggerProvider swaggerProvider)
  at Microsoft.AspNetCore.Authentication.AuthenticationMiddleware.Invoke(HttpContext context)
  at Jellyfin.Api.Middleware.RobotsRedirectionMiddleware.Invoke(HttpContext httpContext)
  at Jellyfin.Api.Middleware.LegacyEmbyRouteRewriteMiddleware.Invoke(HttpContext httpContext)
  at Jellyfin.Api.Middleware.ResponseTimeMiddleware.Invoke(HttpContext context, IServerConfigurationManager serverConfigurationManager)
  at Jellyfin.Api.Middleware.ExceptionMiddleware.Invoke(HttpContext context)

I seem to be unable to identify from the log the root cause of the issue, where could/should I look next?

Thanks in advance for any help