Aspire 9 on macOS 15.1 won't launch due to "The JSON-RPC connection with the remote party was lost before the request could complete."

[JamesAlexander42]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

Similar to issue #5860 but new since updating to macOS 15.1, the 9.0 dotnet aspire templates and updating the solution to aspire 9. I should also note this happens immediately when using the new starter template. The error "The JSON-RPC connection with the remote party was lost before the request could complete." occurring on F5 in VS Code used to happen until the update to .net 8 or using .net 9 with aspire 8.

Interestingly enough, it doesn't happen to existing or new aspire 8 projects. If I create a new vanilla start aspire 9 project via dotnet new aspire-starter and then attempt to debug app host, I get the error on macOS 15.1.

Odder still is that I've only updated my Mac Studio to 15.1 but my MacBook Pro is on 15.0. The exact same aspire 9 repo/solution on 15.0 without issue.

Installed Workload Id Manifest Version Installation Source

aspire 8.2.2/8.0.100 SDK 9.0.100

C# Dev Kit v1.13.9

Expected Behavior

On F5 the AppHost and related projects will start successfully without an error of "The JSON-RPC connection with the remote party was lost before the request could complete."

Steps To Reproduce

• macOS 15.1
• updated aspire templates
• dotnet 9.0.1
• mkdir aspire-starter-test
• cd aspire-starter-test
• dotnet new aspire-starter
• VS Code with C# DevKit v1.13.9
• Right click on .AppHost project and select Debug -> Start New Instance

Exceptions (if any)

Running on macOS 15.0 appears to work fine

.NET Version info

.NET SDK:
Version: 9.0.100
Commit: 59db016f11
Workload version: 9.0.100-manifests.c6f19616
MSBuild version: 17.12.7+5b8665660

Runtime Environment:
OS Name: Mac OS X
OS Version: 15.1
OS Platform: Darwin
RID: osx-arm64
Base Path: /usr/local/share/dotnet/sdk/9.0.100/

.NET workloads installed:
[aspire]
Installation Source: SDK 9.0.100
Manifest Version: 8.2.2/8.0.100
Manifest Path: /usr/local/share/dotnet/sdk-manifests/8.0.100/microsoft.net.sdk.aspire/8.2.2/WorkloadManifest.json
Install Type: FileBased

Configured to use loose manifests when installing new manifests.

Host:
Version: 9.0.0
Architecture: arm64
Commit: 9d5a6a9aa4

.NET SDKs installed:
7.0.304 [/usr/local/share/dotnet/sdk]
8.0.100 [/usr/local/share/dotnet/sdk]
8.0.101 [/usr/local/share/dotnet/sdk]
9.0.100 [/usr/local/share/dotnet/sdk]

.NET runtimes installed:
Microsoft.AspNetCore.App 7.0.7 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 8.0.0 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 8.0.1 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 9.0.0 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
Microsoft.NETCore.App 7.0.7 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
Microsoft.NETCore.App 8.0.0 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
Microsoft.NETCore.App 8.0.1 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
Microsoft.NETCore.App 9.0.0 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]

Other architectures found:
None

Environment variables:
Not set

global.json file:
Not found

Learn more:
https://aka.ms/dotnet/info

Download .NET:
https://aka.ms/dotnet/download

Anything else?

No response

[JamesAlexander42]

So interestingly enough, I realized that my Mac Studio is running an older version of .net core 8 (8.0.1). I updated just .net core 8 (even though I'm doing all .net core 9 stuff and using aspire 9) to .net 8.0.11 and the issue appears to be resolved. Odder still is on another MacBook, I only have .net 9 installed and also don't have the issue.

[joperezr]

Thanks for the confirmation @JamesAlexander42, just to confirm, can you share the version of the 8.0 SDK (who brought that 8.0.11) so we can validate things are working as expected?

[quoctuancqt]

I’ve already faced this issue since I updated net 9 and aspire 9.