run session could not be started

[Paulo Morgado (paulomorgado)]

I'm trying to run a project with a project path:

var builder = DistributedApplication.CreateBuilder(args);

var idp = builder.AddProject(name: "visionbox.connext.identity", @"..\..\XXX\XXX.csproj");

var host = builder.Build();

host.Run();

and Im getting these errors:

Aspire.Hosting.Dcp.dcpctrl.ExecutableReconciler: Error: run session could not be started	{"Controller": "usvc-dev.developer.microsoft.com/executable-reconciler", "Executable": {"name":"xxx-473r320"}, "Reconciliation": 2, "State": "", "ExecutionID": "", "Status": "500 Internal Server Error", "Body": ""}
...
Aspire.Hosting.Dcp.dcpctrl.ExecutableReconciler: Error: failed to create temporary file for capturing standard output data	{"Controller": "usvc-dev.developer.microsoft.com/executable-reconciler", "Executable": {"name":"xxx-473r320"}, "Reconciliation": 3, "State": "Starting", "ExecutionID": "", "error": "open C:\\Users\\PAULO\\AppData\\Local\\Temp\\visionbox.connext.identity-473r320_out_43fc38c5-0550-4874-a520-5a809d0e3a68: The file exists."}

Aspire.Hosting.Dcp.dcpctrl.ExecutableReconciler: Error: failed to create temporary file for capturing standard error data	{"Controller": "usvc-dev.developer.microsoft.com/executable-reconciler", "Executable": {"name":"visionbox.connext.identity-473r320"}, "Reconciliation": 3, "State": "Starting", "ExecutionID": "", "error": "open C:\\Users\\PAULO\\AppData\\Local\\Temp\\xxx-473r320_err_43fc38c5-0550-4874-a520-5a809d0e3a68: The file exists."}

Aspire.Hosting.Dcp.dcpctrl.ExecutableReconciler: Error: run session could not be started	{"Controller": "usvc-dev.developer.microsoft.com/executable-reconciler", "Executable": {"name":"visionbox.connext.identity-473r320"}, "Reconciliation": 3, "State": "Starting", "ExecutionID": "", "Status": "500 Internal Server Error", "Body": ""}

...

The same project runs as project reference in another Aspire host.

What am I missing here?

[Paulo Morgado (paulomorgado)]

And now it works. Go figure.

[Paulo Morgado (paulomorgado)]

It works with path, only if there's also a project reference.

[Damian Edwards (DamianEdwards)]

Known issue #1486

[Perry Stathopoulos (pstatho)]

Had a similar issue, but I was working with VS2022 and aspire workload. Installed VS Preview and issue went away. So there is something that VS Preview is adding that made it work. Hope that helps

[Civilise (ACivilise)]

I had the same issue with Visual Studio 2022 Version 17.14.0. I updated to 17.14.3 and it fixed it...

[tushar-kesare]

I am running Visual Studio 2026 Professional Insiders [12224.323] and having this problem. AddProject() by csproj path does not work when I hit F5. But it does run if I do "dotnet run .\AspireProject.csproj".

[Damian Edwards (DamianEdwards)]

this is a known limitation. The newly released Project Resource v2 API fixes this problem.