`ObjectDisposedException` thrown when hosts get recycled

On August 15th, 2025 around 17:40 UTC we started seeing `ObjectDisposedException` thrown by the function hosts in both our production and staging environments (no code changes or configuration changes were made within a week of this behavior starting).

The stacktraces make no reference to our code, and the exception occurs a few dozen times per day:

```
System.ObjectDisposedException:
at Microsoft.Extensions.DependencyInjection.ServiceLookup.ThrowHelper.ThrowObjectDisposedException (Microsoft.Extensions.DependencyInjection, Version=8.0.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60)
at Microsoft.Extensions.DependencyInjection.ServiceProvider.GetService (Microsoft.Extensions.DependencyInjection, Version=8.0.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60)
at Microsoft.Extensions.DependencyInjection.ServiceLookup.ServiceProviderEngineScope.GetService (Microsoft.Extensions.DependencyInjection, Version=8.0.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60)
at Microsoft.Extensions.DependencyInjection.ServiceProviderServiceExtensions.GetRequiredService (Microsoft.Extensions.DependencyInjection.Abstractions, Version=8.0.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60)
at Microsoft.Extensions.DependencyInjection.ServiceProviderServiceExtensions.GetRequiredService (Microsoft.Extensions.DependencyInjection.Abstractions, Version=8.0.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60)
at Microsoft.AspNetCore.Mvc.ObjectResult.ExecuteResultAsync (Microsoft.AspNetCore.Mvc.Core, Version=8.0.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60)
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker+<g__Logged|22_0>d.MoveNext (Microsoft.AspNetCore.Mvc.Core, Version=8.0.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60)
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw (System.Private.CoreLib, Version=8.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (System.Private.CoreLib, Version=8.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (System.Private.CoreLib, Version=8.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker+<g__Awaited|30_0>d`2.MoveNext (Microsoft.AspNetCore.Mvc.Core, Version=8.0.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60)
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw (System.Private.CoreLib, Version=8.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Rethrow (Microsoft.AspNetCore.Mvc.Core, Version=8.0.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60)
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.ResultNext (Microsoft.AspNetCore.Mvc.Core, Version=8.0.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60)
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.InvokeResultFilters (Microsoft.AspNetCore.Mvc.Core, Version=8.0.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60)
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw (System.Private.CoreLib, Version=8.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (System.Private.CoreLib, Version=8.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (System.Private.CoreLib, Version=8.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker+<g__Awaited|25_0>d.MoveNext (Microsoft.AspNetCore.Mvc.Core, Version=8.0.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60)
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw (System.Private.CoreLib, Version=8.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Rethrow (Microsoft.AspNetCore.Mvc.Core, Version=8.0.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60)
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Next (Microsoft.AspNetCore.Mvc.Core, Version=8.0.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60)
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker+<g__Awaited|20_0>d.MoveNext (Microsoft.AspNetCore.Mvc.Core, Version=8.0.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60)
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw (System.Private.CoreLib, Version=8.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (System.Private.CoreLib, Version=8.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (System.Private.CoreLib, Version=8.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker+<g__Logged|17_1>d.MoveNext (Microsoft.AspNetCore.Mvc.Core, Version=8.0.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60)
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw (System.Private.CoreLib, Version=8.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker+<g__Logged|17_1>d.MoveNext (Microsoft.AspNetCore.Mvc.Core, Version=8.0.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60)
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw (System.Private.CoreLib, Version=8.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (System.Private.CoreLib, Version=8.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (System.Private.CoreLib, Version=8.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at Microsoft.AspNetCore.Builder.RouterMiddleware+d__4.MoveNext (Microsoft.AspNetCore.Routing, Version=8.0.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60)
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw (System.Private.CoreLib, Version=8.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (System.Private.CoreLib, Version=8.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (System.Private.CoreLib, Version=8.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at Microsoft.Azure.WebJobs.Script.WebHost.Middleware.FunctionInvocationMiddleware+d__2.MoveNext (Microsoft.Azure.WebJobs.Script.WebHost, Version=4.1041.0.0, Culture=neutral, PublicKeyToken=null: /_/src/WebJobs.Script.WebHost/Middleware/FunctionInvocationMiddleware.cs:39)
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw (System.Private.CoreLib, Version=8.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (System.Private.CoreLib, Version=8.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (System.Private.CoreLib, Version=8.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at Microsoft.Azure.WebJobs.Script.WebHost.Middleware.ExceptionMiddleware+d__3.MoveNext (Microsoft.Azure.WebJobs.Script.WebHost, Version=4.1041.0.0, Culture=neutral, PublicKeyToken=null: /_/src/WebJobs.Script.WebHost/Middleware/ExceptionMiddleware.cs:27)
```

Reviewing our logs suggests the issue has to do with the host thrashing a bit on starup:
```
11:43:24.893 AM | Trace | Severity level: Information, Message: Initializing function HTTP routes
11:43:24.893 AM | Trace | Severity level: Information, Message: Host initialized (33ms)
11:43:25.059 AM | Trace | Severity level: Information, Message: Stopping JobHost
11:43:25.061 AM | Trace | Severity level: Information, Message: Job host stopped
11:43:25.103 AM | Trace | Severity level: Information, Message: Host started (242ms)
11:43:25.103 AM | Trace | Severity level: Information, Message: Job host started
11:43:25.131 AM | Exception | Call Stack: System.ObjectDisposedException:
11:43:25.131 AM | Trace | Severity level: Error, Message: An unhandled host error has occurred.
11:43:26.837 AM | Trace | Severity level: Information, Message: Worker process started and initialized.
````

Other relevant info:
- We're on isolated .net9
- Our function is HTTP triggered
- We're on the premium plan (EP1)
- We're using c# and on all the latest SDK versions (Microsoft.Azure.Functions.Worker is 2.0.0 and Microsoft.Azure.Functions.Worker.Sdk is 2.0.5)
- We're familiar with best practices r.e. service scopes and have audited out codebase to confirm we're abiding by them (note that this exception started occurring in the absence of any code change).

Thanks in advance!

Start with the host lifecycle log sequence showing JobHost stopping and starting, then inspect src/WebJobs.Script.WebHost/Middleware/FunctionInvocationMiddleware.cs at line 39 and ExceptionMiddleware.cs at line 27. Reproduce the isolated .NET 9 HTTP-triggered startup or recycling scenario and trace the disposed service provider. Done means identifying the host lifecycle race, fixing it, and adding regression coverage for the exception.

Written by the indexing model from the issue text.