{"record":{"id":"b06d1eb30c541336","repo":"apache/druid","slug":"cannot-open-reader","errorCode":null,"errorMessage":"Cannot open reader","messagePattern":"Cannot open reader","errorType":"exception","errorClass":"UnsupportedOperationException (UOE)","httpStatus":null,"severity":"error","filePath":"extensions-core/s3-extensions/src/main/java/org/apache/druid/storage/s3/S3DataSegmentPuller.java","lineNumber":248,"sourceCode":"        }\n        catch (SdkException e) {\n          if (e instanceof S3Exception && ((S3Exception) e).statusCode() == 404) {\n            throw new IOE(e, \"IndexFile[s3://%s/%s] does not exist\", coords.getBucket(), coords.getPath());\n          }\n          throw new IOE(e, \"Could not load S3 URI [%s]\", uri);\n        }\n      }\n\n      @Override\n      public OutputStream openOutputStream()\n      {\n        throw new UOE(\"Cannot stream S3 output\");\n      }\n\n      @Override\n      public Reader openReader(boolean ignoreEncodingErrors)\n      {\n        throw new UOE(\"Cannot open reader\");\n      }\n\n      @Override\n      public CharSequence getCharContent(boolean ignoreEncodingErrors)\n      {\n        throw new UOE(\"Cannot open character sequence\");\n      }\n\n      @Override\n      public Writer openWriter()\n      {\n        throw new UOE(\"Cannot open writer\");\n      }\n\n      @Override\n      public long getLastModified()\n      {\n        if (s3InputStream != null) {","sourceCodeStart":230,"sourceCodeEnd":266,"githubUrl":"https://github.com/apache/druid/blob/9b90983fd291f26935af934383ce360473179e4d/extensions-core/s3-extensions/src/main/java/org/apache/druid/storage/s3/S3DataSegmentPuller.java#L230-L266","documentation":"Unsupported-operation sentinel in S3DataSegmentPuller's FileObject: openReader() is rejected because character-reader semantics are not meaningful for a binary S3 object; the FileObject only supports binary InputStream access.","triggerScenarios":"Thrown at extensions-core/s3-extensions/src/main/java/org/apache/druid/storage/s3/S3DataSegmentPuller.java:248 when the library encounters an invalid state.","commonSituations":"See trigger scenarios.","solutions":["Use openInputStream() and wrap with an explicit charset Reader if text access is required.","Do not use this FileObject with APIs that require openReader()."],"exampleFix":null,"handlingStrategy":"validation","validationCode":null,"typeGuard":null,"tryCatchPattern":null,"preventionTips":[],"tags":[],"backgroundTag":null,"analyzedSha":"9b90983fd291f26935af934383ce360473179e4d","analyzedAt":"2026-09-07T13:32:30.957Z","contentChangedAt":"2026-09-07T13:32:30.957Z","schemaVersion":2},"datasetVersion":"2026-09-17T15:17:12.973Z"}