I have made an ASP.NET Core (.Net 5) Web API which works perfectly fine on my local machine. And actually all contorllers except one work fine too. When I make a Post Request to my DataStoreController I get the following exception:

System.BadImageFormatException: Bad binary signature. (0x80131192)
at System.Runtime.CompilerServices.RuntimeHelpers._CompileMethod(RuntimeMethodHandleInternal method) at System.Reflection.Emit.DynamicMethod.CreateDelegate(Type delegateType, Object target) at System.Linq.Expressions.Compiler.LambdaCompiler.Compile(LambdaExpression lambda) at System.Linq.Expressions.Expression`1.Compile() at Microsoft.Extensions.Internal.ObjectMethodExecutor.GetExecutor(MethodInfo methodInfo, TypeInfo targetTypeInfo) at Microsoft.Extensions.Internal.ObjectMethodExecutor..ctor(MethodInfo methodInfo, TypeInfo targetTypeInfo, Object[] parameterDefaultValues) at Microsoft.Extensions.Internal.ObjectMethodExecutor.Create(MethodInfo methodInfo, TypeInfo targetTypeInfo, Object[] parameterDefaultValues) at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvokerCache.GetCachedResult(ControllerContext controllerContext) at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvokerProvider.OnProvidersExecuting(ActionInvokerProviderContext context) at Microsoft.AspNetCore.Mvc.Infrastructure.ActionInvokerFactory.CreateInvoker(ActionContext actionContext) at Microsoft.AspNetCore.Mvc.Routing.ActionEndpointFactory.<>c__DisplayClass7_0.b__0(HttpContext context) at Microsoft.AspNetCore.Routing.EndpointMiddleware.Invoke(HttpContext httpContext) --- End of stack trace from previous location --- at Swashbuckle.AspNetCore.SwaggerUI.SwaggerUIMiddleware.Invoke(HttpContext httpContext) at Swashbuckle.AspNetCore.Swagger.SwaggerMiddleware.Invoke(HttpContext httpContext, ISwaggerProvider swaggerProvider) at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware.Invoke(HttpContext context)

I have tried what would happen if I made the Method inside the Controller empty and just return null - but still the same error. The only differnce package-wise to the other controllers is that the DataStoreController uses the Stackexchange.Redis NuGet Package.

My gut feeling tells me that this is a weird Azure Bug, but I would love to get some opinions/advices/answers from you.