What causes "Failed to search for packages. Exit code: {0}." in microsoft/aspire?

Check CLI debug logs for the logged stderr/stdout of the failed search to see the underlying NuGet error

microsoft/aspire · error · NuGetPackageCacheException

Failed to search for packages. Exit code

Error message

Failed to search for packages. Exit code: {0}.

What it means

After running aspire-managed nuget search, BundleNuGetPackageCache checks the process exit code. A non-zero exit code means the search command failed (e.g. network/feed errors), so it logs stderr/stdout and throws NuGetPackageCacheException with a message embedding the exit code.

Solutions

Check CLI debug logs for the logged stderr/stdout of the failed search to see the underlying NuGet error
Verify network access to the NuGet source(s) and configure the proxy correctly
Fix or remove the nuget.config in the working directory (or pass a valid --nuget-config)
Ensure NuGet credential providers are installed for authenticated feeds and retry

Defensive patterns

Strategy: retry

Validate before calling

// Validate feed reachability before search
curl -fsSL https://api.nuget.org/v3/index.json > /dev/null || echo "NuGet source unreachable"

Try / catch

try
{
    await cache.SearchPackagesAsync(...);
}
catch (NuGetPackageCacheException ex) when (ex.Message.StartsWith("Failed to search for packages"))
{
    // inspect CLI debug logs for stderr; fix feed/proxy/credentials; retry
}

Prevention

Configure proxy and corporate firewall rules for NuGet endpoints in advance
Install NuGet credential providers for any authenticated feeds
Validate nuget.config files in project directories before running package commands
Use --verbose/debug logging when debugging feed issues

When it happens

Trigger: Any `packages` search or version query where the aspire-managed `nuget search` helper process exits non-zero — unreachable NuGet source, bad nuget.config, auth failure on a private feed, or invalid query arguments.

Common situations: Corporate proxy blocking nuget.org; private Azure DevOps feed requiring credentials with no configured credential provider; malformed nuget.config in the working directory or passed via --nuget-config; offline machine.

Understand the failure class

Background: 'Something went wrong' / 'Request failed (500)' / 'HTTP error! status: 404' — what failed HTTP requests actually mean and how to find the real cause — this error's family across 28 libraries.

Related errors

AI-assisted analysis of microsoft/aspire@25830f84bd (2026-09-16). Data as JSON: /api/errors/0ea51323964ea33c. Report an issue: GitHub.

Appendix: source

Thrown at src/Aspire.Cli/NuGet/BundleNuGetPackageCache.cs:215

            environmentVariables: environmentVariables,
            // A package search against a slow/unresponsive NuGet source can hang. LayoutProcessRunner uses
            // this to bind the helper to the CLI's Windows kill-on-close job (and, on non-Windows, to
            // instead arm the cooperative parent-liveness watchdog) so a hard-killed CLI cannot leak it.
            killOnParentExit: true,
            ct: cancellationToken).ConfigureAwait(false);

        // Log stderr output (verbose info from NuGetHelper)
        if (!string.IsNullOrWhiteSpace(error))
        {
            _logger.LogDebug("NuGetHelper stderr: {Error}", error);
        }

        if (exitCode != 0)
        {
            _logger.LogError("NuGet search failed with exit code {ExitCode}", exitCode);
            _logger.LogError("NuGet search stderr: {Error}", error);
            _logger.LogError("NuGet search stdout: {Output}", output);
            throw new NuGetPackageCacheException(string.Format(CultureInfo.CurrentCulture, ErrorStrings.FailedToSearchForPackages, exitCode));
        }

        _logger.LogDebug("NuGet search returned {Length} bytes", output?.Length ?? 0);

        try
        {
            if (string.IsNullOrEmpty(output))
            {
                _logger.LogWarning("NuGet search returned empty output");
                return [];
            }

            // The aspire-managed helper writes the search result as JSON to stdout, but a NuGet credential
            // provider can write diagnostics before or after that payload. Extract exactly one complete root object
            // with the expected bundle-search shape so provider diagnostics cannot be deserialized as the result.
            // See https://github.com/microsoft/aspire/issues/19339.
            var result = JsonSerializer.Deserialize(PackageUpdateHelpers.ExtractJsonPayload(output, IsBundleSearchPayload), BundleSearchJsonContext.Default.BundleSearchResult);
            if (result?.Packages is null)

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