@mkArtakMSFT

Thanks for contacting us.

We're moving this issue to the .NET 9 Planning milestone for future evaluation / consideration. We would like to keep this around to collect more feedback, which can help us with prioritizing this work. We will re-evaluate this issue, during our next planning meeting(s).
If we later determine, that the issue has no community involvement, or it's very rare and low-impact issue, we will close it - so that the team can focus on more important and high impact issues.
To learn more about what to expect next and how this issue will be handled you can read more about our triage process here.

@javiercn It seems like there is a code path that should be invalidating the cache on Hot Reload.

However, try the following repro steps:

1. Unzip Repro.zip and open WebAppCachingType.sln in VS
2. F5
3. Exception should be reported:

An unhandled exception occurred while processing the request.
InvalidCastException: Unable to cast object of type 'System.String[]' to type 'System.Collections.Generic.List`1[System.String]'.
Microsoft.AspNetCore.Components.Reflection.PropertySetter.CallPropertySetter<TTarget, TValue>(Action<TTarget, TValue> setter, object target, object value)

4. Change PhotoList.razor from

public List<string> Photos { get; set; } = [];

to

public IEnumerable<string> Photos { get; set; } = [];

5. Apply change (Hot Reload)
6. The exception is still thrown with the old type

The cache doesn't seem to be cleared:

Placing function breakpoint to Microsoft.AspNetCore.Components.Reflection.ComponentProperties.SetProperties and stepping shows the cache is not empty

Turns out that OnDeltaApplied event is not subscribed to when Hot Reload happens:

Once this is addressed we might hit dotnet/runtime#75154.