{"record":{"id":"4e56d34bb2bb8fd8","repo":"LykosAI/StabilityMatrix","slug":"pip-show-returned-no-output-for-package-packagename-result","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/PyVenvRunner.cs","lineNumber":384,"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":366,"sourceCodeEnd":402,"githubUrl":"https://github.com/LykosAI/StabilityMatrix/blob/af93d6ef57c01cd890d7e0ad0a9ea8c9fcda3002/StabilityMatrix.Core/Python/PyVenvRunner.cs#L366-L402","documentation":"PipShow throws ProcessException when pip exits 0 but its stdout is empty/whitespace. Since `pip show` on success always prints package metadata, empty output means an unexpected state (e.g. stderr had warnings only, or output was swallowed). The message carries the StandardError for diagnosis.","triggerScenarios":"PipShow(packageName) returns exit code 0 but result.StandardOutput is null/empty; PipShowResult.Parse would otherwise fail.","commonSituations":"Pip stdout redirected or truncated by an environment; a shimmed/wrapped pip that prints nothing; locale/encoding problems; unusual pip forks emitting to stderr.","solutions":["Inspect the StandardError in the message for clues from the pip process.","Re-run `venv/bin/python -m pip show <pkg>` manually to see whether output is produced.","Check that no wrapper script/alias overrides pip within the venv.","Retry after reinstalling the package or updating pip in the venv."],"exampleFix":"// before\nvar result = venv.PipShow(\"requests\").Packages[0];\n// after\ntry { var result = venv.PipShow(\"requests\").Packages[0]; }\ncatch (ProcessException ex) { Logger.Warn(ex, \"pip show empty output\"); return null; }","handlingStrategy":"try-catch","validationCode":"var listed = await venv.PipList();\nbool exists = listed.Any(p => p.PackageName == packageName);","typeGuard":null,"tryCatchPattern":"try { return venv.PipShow(pkg); }\ncatch (ProcessException ex) { Logger.Warn(ex, \"pip show empty output for {Pkg}\", pkg); return null; }","preventionTips":["Validate output non-empty before calling Parse in your own wrappers","Avoid pip wrappers/shims that suppress stdout","Retry once on empty output before surfacing the error"],"tags":["python","pip","empty-output","subprocess"],"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"}