{"record":{"id":"00a9fc0588763fde","repo":"apache/beam","slug":"error-reading-state-v","errorCode":null,"errorMessage":"error reading state: %v","messagePattern":"error reading state: (.+?)","errorType":"exception","errorClass":null,"httpStatus":null,"severity":"error","filePath":"sdks/go/pkg/beam/io/fileio/match.go","lineNumber":381,"sourceCode":"}\n\nfunc keyByPath(md FileMetadata) (string, FileMetadata) {\n\treturn md.Path, md\n}\n\ntype dedupFn struct {\n\tState state.Value[struct{}]\n}\n\nfunc (fn *dedupFn) ProcessElement(\n\tsp state.Provider,\n\t_ string,\n\tmd FileMetadata,\n\temit func(FileMetadata),\n) error {\n\t_, ok, err := fn.State.Read(sp)\n\tif err != nil {\n\t\treturn fmt.Errorf(\"error reading state: %v\", err)\n\t}\n\n\tif !ok {\n\t\temit(md)\n\t\tif err := fn.State.Write(sp, struct{}{}); err != nil {\n\t\t\treturn fmt.Errorf(\"error writing state: %v\", err)\n\t\t}\n\t}\n\n\treturn nil\n}\n\ntype dedupUnmodifiedFn struct {\n\tState state.Value[int64]\n}\n\nfunc (fn *dedupUnmodifiedFn) ProcessElement(\n\tsp state.Provider,","sourceCodeStart":363,"sourceCodeEnd":399,"githubUrl":"https://github.com/apache/beam/blob/12126d8942aaf848030c478b4c6a28c6af861c66/sdks/go/pkg/beam/io/fileio/match.go#L363-L399","documentation":"In fileio's matched-file filter DoFn, ProcessElement reads the pipeline State cell (fn.State.Read(sp)) that tracks which files were already emitted. If the state read itself fails (as opposed to returning ok=false), the error is wrapped with this message. This is a state-management/runtime failure, not a file problem.","triggerScenarios":"fn.State.Read(sp) returns a non-nil err in ProcessElement (match.go:381): the runner's state backend (e.g. Flink/Kafka/state API) is unavailable, the state cell is corrupted, or the state bag fails to decode.","commonSituations":"Runner state backend outage or misconfiguration; using a runner that lacks full state API support; state bag type incompatibility after upgrading the pipeline code under an existing job/state store.","solutions":["Check the wrapped %v error and the runner's state backend health/logs (Flink checkpoints, Dataflow state service)","Verify the runner supports the Beam state API and that the state cell type hasn't changed between job versions","Retry the pipeline after restoring backend availability; transient read failures usually resolve","If state is unnecessary for your use case, run MatchAll without the dedup/filter step to avoid the state dependency"],"exampleFix":null,"handlingStrategy":"retry","validationCode":null,"typeGuard":null,"tryCatchPattern":"_, ok, err := fn.State.Read(sp)\nif err != nil {\n\tif isTransient(err) { return retryRead(sp) }\n\treturn fmt.Errorf(\"state read failed: %w\", err)\n}","preventionTips":["Confirm the runner fully supports the Beam state API before using stateful fileio","Monitor state backend health (checkpointing, state service) and alert on failures","Keep state cell types stable across pipeline upgrades to avoid decode failures"],"tags":["state","beam","runner","fileio"],"backgroundTag":"file-read-failed","analyzedSha":"12126d8942aaf848030c478b4c6a28c6af861c66","analyzedAt":"2026-09-13T01:50:10.254Z","contentChangedAt":"2026-09-13T01:50:10.254Z","schemaVersion":2},"datasetVersion":"2026-09-20T03:17:13.778Z"}