{"record":{"id":"c787862d49c4d2c9","repo":"LykosAI/StabilityMatrix","slug":"pip-show-returned-no-output-for-package-packagename-result-c78786","errorCode":null,"errorMessage":"pip show returned no output for package '{packageName}': {result.StandardError}","messagePattern":"pip show returned no output for package '(.+?)': (.+?)","errorType":"exception","errorClass":"ProcessException","httpStatus":null,"severity":"error","filePath":"StabilityMatrix.Core/Python/UvVenvRunner.cs","lineNumber":401,"sourceCode":"            || result.StandardError?.Contains(\"Package(s) not found\", StringComparison.OrdinalIgnoreCase)\n                == true;\n\n        if (packageNotFound)\n        {\n            return null;\n        }\n\n        // Check return code\n        if (result.ExitCode != 0)\n        {\n            throw new ProcessException(\n                $\"pip show failed with code {result.ExitCode}: {result.StandardOutput}, {result.StandardError}\"\n            );\n        }\n\n        if (string.IsNullOrWhiteSpace(result.StandardOutput))\n        {\n            throw new ProcessException(\n                $\"pip show returned no output for package '{packageName}': {result.StandardError}\"\n            );\n        }\n\n        return PipShowResult.Parse(result.StandardOutput);\n    }\n\n    /// <summary>\n    /// Run a pip index command, return result as PipIndexResult.\n    /// </summary>\n    public async Task<PipIndexResult?> PipIndex(\n        string packageName,\n        string? indexUrl = null,\n        bool includePrerelease = false\n    )\n    {\n        if (!File.Exists(PipPath))\n        {","sourceCodeStart":383,"sourceCodeEnd":419,"githubUrl":"https://github.com/LykosAI/StabilityMatrix/blob/af93d6ef57c01cd890d7e0ad0a9ea8c9fcda3002/StabilityMatrix.Core/Python/UvVenvRunner.cs#L383-L419","documentation":"UvVenvRunner.PipShow throws this ProcessException when `uv pip show` exits successfully (code 0) but StandardOutput is empty or whitespace, so PipShowResult.Parse would have nothing to parse. The package-not-found case is handled separately (returns null), so an empty-but-successful result means pip gave an inconsistent/blank response — usually stderr (included in the message) explains why.","triggerScenarios":"Calling PipShow(packageName) where the subprocess returns exit code 0 but no stdout: pip emitting only errors to stderr while still exiting 0, an unusual uv version suppressing show output, or output redirection/capture producing nothing.","commonSituations":"Odd uv/pip builds with nonstandard show output; environment (env vars, locale) altering pip behavior; stdout swallowed by a misconfigured ProcessRunner capture; exotic package metadata that makes pip print nothing.","solutions":["Check the StandardError text in the exception message for pip's explanation.","Run the same `uv pip show <pkg> --python <venvPython>` command manually to reproduce and inspect raw output.","Update uv to a current version so `pip show` emits standard output.","If the environment is suspect, recreate the venv and retry the query."],"exampleFix":"// before: assuming a null return covers all negative outcomes\nvar info = await runner.PipShow(pkg);\n// after: also handle the empty-output exception\nPipShowResult? info;\ntry { info = await runner.PipShow(pkg); }\ncatch (ProcessException ex) when (ex.Message.Contains(\"returned no output\")) {\n    info = null; // treat as unknown/uninstalled after logging ex.Message\n}","handlingStrategy":"try-catch","validationCode":"var probe = await ProcessRunner.GetProcessResultAsync(runner.UvExecutablePath, new[] { \"--version\" }, null, null);\nif (probe.ExitCode != 0) throw new InvalidOperationException(\"uv broken\");","typeGuard":"static bool UvWorks(UvVenvRunner r) => File.Exists(r.UvExecutablePath);","tryCatchPattern":"try { info = await runner.PipShow(pkg); }\ncatch (ProcessException ex) when (ex.Message.Contains(\"returned no output\")) { info = null; }","preventionTips":["Treat empty stdout with exit 0 as an anomaly; log stderr from the message.","Pin a known-good uv version for reproducible pip output.","Check environment variables passed to the runner don't redirect/suppress output."],"tags":["python","pip","process","empty-output"],"backgroundTag":"empty-response-body","analyzedSha":"af93d6ef57c01cd890d7e0ad0a9ea8c9fcda3002","analyzedAt":"2026-09-12T19:02:43.389Z","contentChangedAt":"2026-09-12T19:02:43.389Z","schemaVersion":2},"datasetVersion":"2026-09-16T04:17:20.429Z"}