Fix DownloadFile to only log errors when all retries are exhausted

[Copilot]

Problem

The DownloadWithRetriesAsync method in DownloadFile.cs was calling Log.LogErrorFromException during retry attempts, even when the download would eventually succeed. This caused MSBuild to mark builds as failed despite successful downloads after retrying.

For example, in https://dev.azure.com/dnceng/internal/_build/results?buildId=2792361, a transient network error was logged as an error:

error : HttpRequestException: No connection could be made because the target machine actively refused it.

The download succeeded on a subsequent retry and produced the expected MSI, but the build was still marked as a failure due to the logged error.

Solution

Moved Log.LogErrorFromException from the retry loop to only execute after all retries are exhausted. Now:

• During retry attempts: Only informational messages are logged via Log.LogMessage
• After successful retry: No errors are logged, build succeeds ✅
• After all retries fail: Error with full stack trace is logged, build fails correctly ❌

Changes

Single line change in src/Microsoft.DotNet.Arcade.Sdk/src/DownloadFile.cs:

• Moved Log.LogErrorFromException(e, true, true, null) from inside the retry loop to inside the if (attempt > Retries) failure block

This ensures errors are only logged when the operation ultimately fails, not during intermediate retry attempts that may succeed.

Fixes the issue originally reported by @mmitche where transient network errors were incorrectly failing builds.

cc: @lewing @joeloff

Original prompt

---

This section details on the original issue you should resolve

<issue_title>DownloadWithRetriesAsync seems to retry, but still log an error?</issue_title>
<issue_description>Seems to be a retryable exception in https://dev.azure.com/dnceng/internal/_build/results?buildId=2792361&view=logs&j=89eea50f-59b5-5921-c3ce-ce40b36fa819&t=483e1309-93e4-5a7a-74de-93b8d658274f&l=11782

I assume it retried and succeeded since I see the build produce an MSI cc @joeloff

The build was still marked as a failure, most likely because of the logged exception:

arcade/src/Microsoft.DotNet.Arcade.Sdk/src/DownloadFile.cs

Line 222 in c32cd13

Log.LogErrorFromException(e, true, true, null);

Pretty sure that LogError should only be in the return false path. @lewing you added in 025a2b3

 D:\a\_work\1\s\src\runtime\artifacts\.packages\microsoft.dotnet.build.tasks.installers\11.0.0-beta.25462.113\build\acquisition\acquire-wix\acquire-wix.proj(36,5): error : HttpRequestException: No connection could be made because the target machine actively refused it. (netcorenativeassets.blob.core.windows.net:443)
  D:\a\_work\1\s\src\runtime\artifacts\.packages\microsoft.dotnet.build.tasks.installers\11.0.0-beta.25462.113\build\acquisition\acquire-wix\acquire-wix.proj(36,5): error :    at System.Net.Http.HttpConnectionPool.ConnectToTcpHostAsync(String host, Int32 port, HttpRequestMessage initialRequest, Boolean async, CancellationToken cancellationToken)
  D:\a\_work\1\s\src\runtime\artifacts\.packages\microsoft.dotnet.build.tasks.installers\11.0.0-beta.25462.113\build\acquisition\acquire-wix\acquire-wix.proj(36,5): error :    at System.Net.Http.HttpConnectionPool.ConnectAsync(HttpRequestMessage request, Boolean async, CancellationToken cancellationToken)
  D:\a\_work\1\s\src\runtime\artifacts\.packages\microsoft.dotnet.build.tasks.installers\11.0.0-beta.25462.113\build\acquisition\acquire-wix\acquire-wix.proj(36,5): error :    at System.Net.Http.HttpConnectionPool.CreateHttp11ConnectionAsync(HttpRequestMessage request, Boolean async, CancellationToken cancellationToken)
  D:\a\_work\1\s\src\runtime\artifacts\.packages\microsoft.dotnet.build.tasks.installers\11.0.0-beta.25462.113\build\acquisition\acquire-wix\acquire-wix.proj(36,5): error :    at System.Net.Http.HttpConnectionPool.InjectNewHttp11ConnectionAsync(QueueItem queueItem)
  D:\a\_work\1\s\src\runtime\artifacts\.packages\microsoft.dotnet.build.tasks.installers\11.0.0-beta.25462.113\build\acquisition\acquire-wix\acquire-wix.proj(36,5): error :    at System.Threading.Tasks.TaskCompletionSourceWithCancellation`1.WaitWithCancellationAsync(CancellationToken cancellationToken)
  D:\a\_work\1\s\src\runtime\artifacts\.packages\microsoft.dotnet.build.tasks.installers\11.0.0-beta.25462.113\build\acquisition\acquire-wix\acquire-wix.proj(36,5): error :    at System.Net.Http.HttpConnectionPool.SendWithVersionDetectionAndRetryAsync(HttpRequestMessage request, Boolean async, Boolean doRequestAuth, CancellationToken cancellationToken)
  D:\a\_work\1\s\src\runtime\artifacts\.packages\microsoft.dotnet.build.tasks.installers\11.0.0-beta.25462.113\build\acquisition\acquire-wix\acquire-wix.proj(36,5): error :    at System.Net.Http.RedirectHandler.SendAsync(HttpRequestMessage request, Boolean async, CancellationToken cancellationToken)
  D:\a\_work\1\s\src\runtime\artifacts\.packages\microsoft.dotnet.build.tasks.installers\11.0.0-beta.25462.113\build\acquisition\acquire-wix\acquire-wix.proj(36,5): error :    at System.Net.Http.SocketsHttpHandler.<SendAsync>g__CreateHandlerAndSendAsync|115_0(HttpRequestMessage request, CancellationToken cancellationToken)
  D:\a\_work\1\s\src\runtime\artifacts\.packages\microsoft.dotnet.build.tasks.installers\11.0.0-beta.25462.113\build\acquisition\acquire-wix\acquire-wix.proj(36,5): error :    at System.Net.Http.HttpClient.<SendAsync>g__Core|83_0(HttpRequestMessage request, HttpCompletionOption completionOption, CancellationTokenSource cts, Boolean disposeCts, CancellationTokenSource pendingRequestsCts, CancellationToken originalCancellationToken)
  D:\a\_work\1\s\src\runtime\artifacts\.packages\microsoft.dotnet.build.tasks.installers\11.0.0-beta.25462.113\build\acquisition\acquire-wix\acquire-wix.proj(36,5): error :    at Microsoft.DotNet.Arcade.Sdk.DownloadFile.DownloadWithRetriesAsync(HttpClient httpClient, String uri) in /_/src/arcade/src/Microsoft.DotNet.Arcade.Sdk/src/DownloadFile.cs:line 184
  D:\a\_work\1\s\src\runtime\artifacts\.packages\microsoft.dotnet.build.tasks.installers\11.0.0-beta.25462.113\build\acquisition\acquire-wix\acquire-wix.proj(36,5): error : SocketException: No connection could be made because the target machine actively refused it.
  D:\a\_work\1\s\src\runtime\artifacts\.packages\microsoft.dotnet.build.tasks.installers\11.0.0-beta.25462.113\build\acquisition\acquire-wix\acquire-wix.proj(36,5): error :    at System.Net.Sockets.Socket.AwaitableSocket...

</details>

Fixes dotnet/arcade#16137

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