Fix --no-build flag error message inconsistency for non-existent project files #49544

Copilot · 2025-06-24T20:47:21Z

The --no-build flag in dotnet run was producing misleading error messages when project files don't exist. This created confusion for developers who would see different error messages depending on whether they used --no-build or not.

Problem

When running dotnet run with a non-existent project file:

Without --no-build: "Project file does not exist." (clear and helpful)
With --no-build: "'xyz.csproj' is not a valid project file." (misleading - suggests the file exists but is malformed)

Example

# Clear error message
$ dotnet run --project xyz.csproj
MSBUILD : error MSB1009: Project file does not exist.
Switch: xyz.csproj

# Misleading error message
$ dotnet run --project xyz.csproj --no-build
'xyz.csproj' is not a valid project file.

Solution

Added a file existence check in the DiscoverProjectFilePath method before attempting to load the project. When a specified project file doesn't exist, both code paths now provide a consistent, clear error message using the existing localized string CmdNonExistentFileErrorDescription.

After the fix

Both cases now show the same clear message:

$ dotnet run --project xyz.csproj --no-build
The provided file path does not exist: xyz.csproj.

$ dotnet run --project xyz.csproj
The provided file path does not exist: xyz.csproj.

Changes

RunCommand.cs: Added file existence validation in DiscoverProjectFilePath method
Test: Added ItProvidesConsistentErrorMessageWhenProjectFileDoesNotExistWithNoBuild to validate the fix

The fix is minimal and surgical - it only adds a file existence check when a project file path is explicitly provided and doesn't exist, ensuring consistent error messaging across both build and no-build scenarios.

Fixes #24591.

Warning

Firewall rules blocked me from connecting to one or more addresses

I tried to connect to the following addresses, but was blocked by firewall rules:

4m6vsblobprodcus384.vsblob.vsassets.io
- Triggering command: /home/REDACTED/work/sdk/sdk/artifacts/bin/redist/Debug/dotnet/dotnet run -v:m (dns block)
- Triggering command: /home/REDACTED/work/sdk/sdk/artifacts/bin/redist/Debug/dotnet/dotnet run -p /home/REDACTED/work/sdk/sdk/artifacts/tmp/Debug/ItWarnsWhenSh---7BBD1F37/MSBuildTestApp.csproj (dns block)
4zjvsblobprodcus390.vsblob.vsassets.io
- Triggering command: /home/REDACTED/work/sdk/sdk/artifacts/bin/redist/Debug/dotnet/dotnet run -v:m (dns block)
- Triggering command: /home/REDACTED/work/sdk/sdk/artifacts/bin/redist/Debug/dotnet/dotnet run -p /home/REDACTED/work/sdk/sdk/artifacts/tmp/Debug/ItWarnsWhenSh---7BBD1F37/MSBuildTestApp.csproj (dns block)
ajhvsblobprodcus363.vsblob.vsassets.io
- Triggering command: /home/REDACTED/work/sdk/sdk/artifacts/bin/redist/Debug/dotnet/dotnet run -v:m (dns block)
- Triggering command: /home/REDACTED/work/sdk/sdk/artifacts/bin/redist/Debug/dotnet/dotnet run -p /home/REDACTED/work/sdk/sdk/artifacts/tmp/Debug/ItWarnsWhenSh---7BBD1F37/MSBuildTestApp.csproj (dns block)
c78vsblobprodcus322.vsblob.vsassets.io
- Triggering command: /home/REDACTED/work/sdk/sdk/artifacts/bin/redist/Debug/dotnet/dotnet run -v:m (dns block)
- Triggering command: /home/REDACTED/work/sdk/sdk/artifacts/bin/redist/Debug/dotnet/dotnet run -p /home/REDACTED/work/sdk/sdk/artifacts/tmp/Debug/ItWarnsWhenSh---7BBD1F37/MSBuildTestApp.csproj (dns block)
d0svsblobprodcus381.vsblob.vsassets.io
- Triggering command: /home/REDACTED/work/sdk/sdk/artifacts/bin/redist/Debug/dotnet/dotnet run -v:m (dns block)
- Triggering command: /home/REDACTED/work/sdk/sdk/artifacts/bin/redist/Debug/dotnet/dotnet run -p /home/REDACTED/work/sdk/sdk/artifacts/tmp/Debug/ItWarnsWhenSh---7BBD1F37/MSBuildTestApp.csproj (dns block)
jd4vsblobprodcus366.vsblob.vsassets.io
- Triggering command: /home/REDACTED/work/sdk/sdk/artifacts/bin/redist/Debug/dotnet/dotnet run -v:m (dns block)
- Triggering command: /home/REDACTED/work/sdk/sdk/artifacts/bin/redist/Debug/dotnet/dotnet run -p /home/REDACTED/work/sdk/sdk/artifacts/tmp/Debug/ItWarnsWhenSh---7BBD1F37/MSBuildTestApp.csproj (dns block)
- Triggering command: /home/REDACTED/work/_temp/ghcca-node/node/bin/node --enable-source-maps /home/REDACTED/work/_temp/copilot-developer-action-main/dist/index.js (dns block)
josvsblobprodcus372.vsblob.vsassets.io
- Triggering command: /home/REDACTED/work/sdk/sdk/artifacts/bin/redist/Debug/dotnet/dotnet run -v:m (dns block)
- Triggering command: /home/REDACTED/work/sdk/sdk/artifacts/bin/redist/Debug/dotnet/dotnet run -p /home/REDACTED/work/sdk/sdk/artifacts/tmp/Debug/ItWarnsWhenSh---7BBD1F37/MSBuildTestApp.csproj (dns block)
k0ivsblobprodcus356.vsblob.vsassets.io
- Triggering command: /home/REDACTED/work/sdk/sdk/artifacts/bin/redist/Debug/dotnet/dotnet run -v:m (dns block)
- Triggering command: /home/REDACTED/work/sdk/sdk/artifacts/bin/redist/Debug/dotnet/dotnet run -p /home/REDACTED/work/sdk/sdk/artifacts/tmp/Debug/ItWarnsWhenSh---7BBD1F37/MSBuildTestApp.csproj (dns block)
k4kvsblobprodcus344.vsblob.vsassets.io
- Triggering command: /home/REDACTED/work/sdk/sdk/artifacts/bin/redist/Debug/dotnet/dotnet run -v:m (dns block)
- Triggering command: /home/REDACTED/work/sdk/sdk/artifacts/bin/redist/Debug/dotnet/dotnet run -p /home/REDACTED/work/sdk/sdk/artifacts/tmp/Debug/ItWarnsWhenSh---7BBD1F37/MSBuildTestApp.csproj (dns block)
nn8vsblobprodcus340.vsblob.vsassets.io
- Triggering command: /home/REDACTED/work/sdk/sdk/artifacts/bin/redist/Debug/dotnet/dotnet run -v:m (dns block)
- Triggering command: /home/REDACTED/work/sdk/sdk/artifacts/bin/redist/Debug/dotnet/dotnet run -p /home/REDACTED/work/sdk/sdk/artifacts/tmp/Debug/ItWarnsWhenSh---7BBD1F37/MSBuildTestApp.csproj (dns block)
pe3vsblobprodcus354.vsblob.vsassets.io
- Triggering command: /home/REDACTED/work/sdk/sdk/artifacts/bin/redist/Debug/dotnet/dotnet run -v:m (dns block)
- Triggering command: /home/REDACTED/work/sdk/sdk/artifacts/bin/redist/Debug/dotnet/dotnet run -p /home/REDACTED/work/sdk/sdk/artifacts/tmp/Debug/ItWarnsWhenSh---7BBD1F37/MSBuildTestApp.csproj (dns block)
rcxvsblobprodcus328.vsblob.vsassets.io
- Triggering command: /home/REDACTED/work/sdk/sdk/artifacts/bin/redist/Debug/dotnet/dotnet run -v:m (dns block)
- Triggering command: /home/REDACTED/work/sdk/sdk/artifacts/bin/redist/Debug/dotnet/dotnet run -p /home/REDACTED/work/sdk/sdk/artifacts/tmp/Debug/ItWarnsWhenSh---7BBD1F37/MSBuildTestApp.csproj (dns block)
ukkvsblobprodcus352.vsblob.vsassets.io
- Triggering command: /home/REDACTED/work/sdk/sdk/artifacts/bin/redist/Debug/dotnet/dotnet run -v:m (dns block)
- Triggering command: /home/REDACTED/work/sdk/sdk/artifacts/bin/redist/Debug/dotnet/dotnet run -p /home/REDACTED/work/sdk/sdk/artifacts/tmp/Debug/ItWarnsWhenSh---7BBD1F37/MSBuildTestApp.csproj (dns block)
yttvsblobprodcus357.vsblob.vsassets.io
- Triggering command: /home/REDACTED/work/sdk/sdk/artifacts/bin/redist/Debug/dotnet/dotnet run -v:m (dns block)
- Triggering command: /home/REDACTED/work/sdk/sdk/artifacts/bin/redist/Debug/dotnet/dotnet run -p /home/REDACTED/work/sdk/sdk/artifacts/tmp/Debug/ItWarnsWhenSh---7BBD1F37/MSBuildTestApp.csproj (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

Configure Actions setup steps to set up my environment, which run before the firewall is enabled
Add the appropriate URLs or hosts to my firewall allow list

💬 Share your feedback on Copilot coding agent for the chance to win a $200 gift card! Click here to start the survey.

…ect files Co-authored-by: marcpopMSFT <[email protected]>

marcpopMSFT · 2025-06-25T22:07:54Z

@copilot there are two failing tests that appear to use the project flag with a nonexistent project and are now hitting this new error. The tests are valid so the best solution is to workaround this.

For RunParserCanGetArgumentFromDoubleDash, I would just create a project called foo.csproj so that the command finds a valid project when it runs.

For MsbuildInvocationIsCorrect, it expects MyProject.csproj but I believe it's copying in HelloWorld.csproj. I would try changing the data driven test to match

Co-authored-by: marcpopMSFT <[email protected]>

Copilot · 2025-06-25T22:16:53Z

@copilot there are two failing tests that appear to use the project flag with a nonexistent project and are now hitting this new error. The tests are valid so the best solution is to workaround this.
...

Fixed both failing tests as suggested:

RunParserCanGetArgumentFromDoubleDash: Created a temporary foo.csproj file for the test so the command finds a valid project
MsbuildInvocationIsCorrect: Changed the test data from "MyProject.csproj" to "HelloWorld.csproj" to match the actual project file being copied from the test asset

Both tests now pass while preserving the original file existence validation functionality. Commit: 47d4222

marcpopMSFT · 2025-06-27T18:55:22Z

@copilot for test RunParserCanGetArgumentFromDoubleDash, can you use CopyTestAsset("HelloWorld") like other tests and you don't need to clean up the project after as we run each test in a different folder?

…Dash test Co-authored-by: marcpopMSFT <[email protected]>

Copilot · 2025-06-27T19:07:51Z

@copilot for test RunParserCanGetArgumentFromDoubleDash, can you use CopyTestAsset("HelloWorld") like other tests and you don't need to clean up the project after as we run each test in a different fo...

Changed the test to use CopyTestAsset("HelloWorld") pattern and removed the manual cleanup code as suggested. The test now follows the same pattern as other tests and runs in its own directory. Commit: 0cdba96

Warning

Firewall rules blocked me from connecting to one or more addresses

I tried to connect to the following addresses, but was blocked by firewall rules:

5rqvsblobprodcus385.vsblob.vsassets.io
- Triggering command: /home/REDACTED/work/sdk/sdk/artifacts/bin/redist/Debug/dotnet/dotnet test --help --configuration Release (dns block)
jd4vsblobprodcus366.vsblob.vsassets.io
- Triggering command: /home/REDACTED/work/sdk/sdk/artifacts/bin/redist/Debug/dotnet/dotnet msbuild /t:Restore /home/REDACTED/work/sdk/sdk/artifacts/tmp/Debug/ItHasAWhySubc---C601CB95/NewtonSoftDependentProject.csproj (dns block)
n3kvsblobprodcus335.vsblob.vsassets.io
- Triggering command: /home/REDACTED/work/sdk/sdk/artifacts/bin/redist/Debug/dotnet/dotnet test --property:VsTestUseMSBuildOutput=false -tl:false --logger console;verbosity=detailed (dns block)
nn8vsblobprodcus340.vsblob.vsassets.io
- Triggering command: /home/REDACTED/work/sdk/sdk/artifacts/bin/redist/Debug/dotnet/dotnet test --property:VsTestUseMSBuildOutput=false -tl:false --logger console;verbosity=detailed (dns block)
vb4vsblobprodcus33.vsblob.vsassets.io
- Triggering command: /home/REDACTED/work/sdk/sdk/artifacts/bin/redist/Debug/dotnet/dotnet test --property:VsTestUseMSBuildOutput=false -tl:false --logger console;verbosity=detailed (dns block)
- Triggering command: dotnet test test/dotnet.Tests/dotnet.Tests.csproj --no-build (dns block)
vwvvsblobprodcus334.vsblob.vsassets.io
- Triggering command: /home/REDACTED/work/sdk/sdk/artifacts/bin/redist/Debug/dotnet/dotnet test --help --configuration Release (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

Configure Actions setup steps to set up my environment, which run before the firewall is enabled
Add the appropriate URLs or hosts to my firewall allow list

Copilot

Pull Request Overview

This PR fixes an inconsistency in error messages when running dotnet run with the --no-build flag on non-existent project files. Previously, the error messages differed between using --no-build and not using it, causing confusion for developers.

Added file existence validation in the DiscoverProjectFilePath method to provide consistent error messaging
Updated tests to use valid project paths and added a new test to verify the fix
Ensures both build and no-build scenarios show the same clear error message for missing project files

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
src/Cli/dotnet/Commands/Run/RunCommand.cs	Added file existence check before project loading to provide consistent error messages
test/dotnet.Tests/CommandTests/Run/GivenDotnetRunBuildsCsProj.cs	Added test case to verify consistent error messaging with --no-build flag
test/dotnet.Tests/CommandTests/Run/RunParserTests.cs	Updated test to use a valid project file path instead of non-existent file
test/dotnet.Tests/CommandTests/MSBuild/GivenDotnetRunInvocation.cs	Updated test parameter to reference valid HelloWorld.csproj instead of MyProject.csproj

Comments suppressed due to low confidence (1)

test/dotnet.Tests/CommandTests/Run/GivenDotnetRunBuildsCsProj.cs:1031

The error message validation is too broad and fragile. Instead of checking for multiple generic phrases, the test should verify the exact expected error message format using the CmdNonExistentFileErrorDescription localized string to ensure the fix works correctly.

                var hasExpectedErrorMessage = stderr.Contains("does not exist") ||

test/dotnet.Tests/CommandTests/Run/GivenDotnetRunBuildsCsProj.cs

marcpopMSFT · 2025-07-25T20:29:12Z

Behavior matches what's reported. The tests look right to me. Someone else will have to review since it was my copilot request.

Initial plan

5028977

Copilot AI assigned Copilot and marcpopMSFT Jun 24, 2025

Copilot started work on behalf of marcpopMSFT June 24, 2025 20:47 View session

Fix --no-build flag error message inconsistency for non-existent proj…

de25601

…ect files Co-authored-by: marcpopMSFT <[email protected]>

Copilot AI changed the title ~~[WIP] '--no-build' flag messes with 'dotnet run' error messages~~ Fix --no-build flag error message inconsistency for non-existent project files Jun 24, 2025

Copilot AI requested a review from marcpopMSFT June 24, 2025 21:11

Copilot finished work on behalf of marcpopMSFT June 24, 2025 21:11

Copilot started work on behalf of marcpopMSFT June 25, 2025 22:07 View session

Fix failing tests caused by new file existence validation

47d4222

Co-authored-by: marcpopMSFT <[email protected]>

Copilot finished work on behalf of marcpopMSFT June 25, 2025 22:17

Copilot started work on behalf of marcpopMSFT June 27, 2025 18:55 View session

Use CopyTestAsset("HelloWorld") for RunParserCanGetArgumentFromDouble…

0cdba96

…Dash test Co-authored-by: marcpopMSFT <[email protected]>

Copilot finished work on behalf of marcpopMSFT June 27, 2025 19:08

marcpopMSFT added 2 commits June 27, 2025 16:00

Fix run parser test to correctly copy the test source

5163b83

Merge branch 'main' into copilot/fix-24591

ae4e61f

This was referenced Jul 17, 2025

dotnet-watch tests failing #40006

Open

The Operation will be canceled. The next steps may not contain expected logs. dotnet/dnceng#3008

Open

Merge branch 'main' into copilot/fix-24591

fe4cefc

Merge branch 'main' into copilot/fix-24591

70e7c55

marcpopMSFT marked this pull request as ready for review July 25, 2025 20:26

Copilot AI review requested due to automatic review settings July 25, 2025 20:26

Copilot AI reviewed Jul 25, 2025

View reviewed changes

test/dotnet.Tests/CommandTests/Run/GivenDotnetRunBuildsCsProj.cs Outdated Show resolved Hide resolved

marcpopMSFT approved these changes Jul 25, 2025

View reviewed changes

marcpopMSFT requested a review from MiYanni July 25, 2025 20:27

Fix nit

dba3398

MiYanni approved these changes Jul 25, 2025

View reviewed changes

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Uh oh!

Fix --no-build flag error message inconsistency for non-existent project files #49544

Fix --no-build flag error message inconsistency for non-existent project files #49544

Copilot AI commented Jun 24, 2025 •

edited

Loading

Uh oh!

marcpopMSFT commented Jun 25, 2025

Uh oh!

Copilot AI commented Jun 25, 2025

Uh oh!

marcpopMSFT commented Jun 27, 2025

Uh oh!

Copilot AI commented Jun 27, 2025 •

edited

Loading

I tried to connect to the following addresses, but was blocked by firewall rules:

Uh oh!

Copilot AI left a comment

Uh oh!

Uh oh!

marcpopMSFT commented Jul 25, 2025

Uh oh!

Uh oh!

Fix --no-build flag error message inconsistency for non-existent project files #49544

Are you sure you want to change the base?

Fix --no-build flag error message inconsistency for non-existent project files #49544

Conversation

Copilot AI commented Jun 24, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Problem

Example

Solution

After the fix

Changes

I tried to connect to the following addresses, but was blocked by firewall rules:

Uh oh!

marcpopMSFT commented Jun 25, 2025

Uh oh!

Copilot AI commented Jun 25, 2025

Uh oh!

marcpopMSFT commented Jun 27, 2025

Uh oh!

Copilot AI commented Jun 27, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

I tried to connect to the following addresses, but was blocked by firewall rules:

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

Pull Request Overview

Reviewed Changes

Uh oh!

Uh oh!

marcpopMSFT commented Jul 25, 2025

Uh oh!

Uh oh!

Copilot AI commented Jun 24, 2025 •

edited

Loading

Copilot AI commented Jun 27, 2025 •

edited

Loading