{"record":{"id":"5dde4020a1bd9896","repo":"mitmproxy/mitmproxy","slug":"expected-headers-to-be-an-iterable-or-dict-but-is","errorCode":null,"errorMessage":"Expected headers to be an iterable or dict, but is {}.","messagePattern":"Expected headers to be an iterable or dict, but is (.+?)\\.","errorType":"validation","errorClass":"TypeError","httpStatus":null,"severity":"error","filePath":"mitmproxy/http.py","lineNumber":609,"sourceCode":"    ) -> \"Request\":\n        \"\"\"\n        Simplified API for creating request objects.\n        \"\"\"\n        # Headers can be list or dict, we differentiate here.\n        if isinstance(headers, Headers):\n            pass\n        elif isinstance(headers, dict):\n            headers = Headers(\n                (\n                    always_bytes(k, \"utf-8\", \"surrogateescape\"),\n                    always_bytes(v, \"utf-8\", \"surrogateescape\"),\n                )\n                for k, v in headers.items()\n            )\n        elif isinstance(headers, Iterable):\n            headers = Headers(headers)  # type: ignore\n        else:\n            raise TypeError(\n                \"Expected headers to be an iterable or dict, but is {}.\".format(\n                    type(headers).__name__\n                )\n            )\n\n        req = cls(\n            \"\",\n            0,\n            method.encode(\"utf-8\", \"surrogateescape\"),\n            b\"\",\n            b\"\",\n            b\"\",\n            b\"HTTP/1.1\",\n            headers,\n            b\"\",\n            None,\n            time.time(),\n            time.time(),","sourceCodeStart":591,"sourceCodeEnd":627,"githubUrl":"https://github.com/mitmproxy/mitmproxy/blob/2ac5b089d953585c66026a53f678270e094e48e5/mitmproxy/http.py#L591-L627","documentation":"Error \"Expected headers to be an iterable or dict, but is {}.\" thrown in mitmproxy/mitmproxy.","triggerScenarios":"Thrown at mitmproxy/http.py:609 when the library encounters an invalid state.","commonSituations":"See trigger scenarios.","solutions":[],"exampleFix":null,"handlingStrategy":null,"validationCode":null,"typeGuard":null,"tryCatchPattern":null,"preventionTips":[],"tags":[],"backgroundTag":null,"analyzedSha":"2ac5b089d953585c66026a53f678270e094e48e5","analyzedAt":"2026-08-26T07:49:02.629Z","schemaVersion":2},"datasetVersion":"2026-08-26T14:46:13.012Z"}