{"record":{"id":"e87dd1a742bc488e","repo":"go-delve/delve","slug":"swiss-table-type-does-not-have-some-required-field","errorCode":null,"errorMessage":"swiss table type does not have some required fields","messagePattern":"swiss table type does not have some required fields","errorType":"error_code","errorClass":"errSwissMapBadType","httpStatus":null,"severity":"error","filePath":"pkg/proc/mapiter.go","lineNumber":382,"sourceCode":"\ntype swissTable struct {\n\tindex  int64\n\tgroups *Variable\n}\n\ntype swissGroup struct {\n\tctrls []byte\n\n\t// GOEXPERIMENT=nomapsplitgroup\n\tslots *Variable\n\n\t// GOEXPERIMENT=mapsplitgroup\n\tkeys, elems *Variable\n}\n\nvar (\n\terrSwissTableCouldNotLoad  = errors.New(\"could not load one of the tables\")\n\terrSwissMapBadType         = errors.New(\"swiss table type does not have some required fields\")\n\terrSwissMapBadTableField   = errors.New(\"swiss table bad table field\")\n\terrSwissMapBadGroupTypeErr = errors.New(\"bad swiss map type, group type lacks some required fields\")\n\terrSwissTableNilGroups     = errors.New(\"bad swiss map, groups pointer is nil\")\n)\n\n// loadTypes determines the correct type for it.dirPtr:  the linker records\n// this type as **table but in reality it is either *[dirLen]*table for\n// large maps or *group for small maps, when it.dirLen == 0.\nfunc (it *mapIteratorSwiss) loadTypes() {\n\ttableptrptrtyp, ok := it.dirPtr.DwarfType.(*godwarf.PtrType)\n\tif !ok {\n\t\tit.v.Unreadable = errSwissMapBadTableField\n\t\treturn\n\t}\n\ttableptrtyp, ok := tableptrptrtyp.Type.(*godwarf.PtrType)\n\tif !ok {\n\t\tit.v.Unreadable = errSwissMapBadTableField\n\t\treturn","sourceCodeStart":364,"sourceCodeEnd":400,"githubUrl":"https://github.com/go-delve/delve/blob/a23773e6c31361e43246bc43a424ee009679b174/pkg/proc/mapiter.go#L364-L400","documentation":"Delve determines the swiss map's table and group types by inspecting the type of it.dirPtr (loadTypes). errSwissMapBadType is returned when the map's DWARF type lacks some required fields Delve needs to decode a swiss map, meaning the runtime type shape does not match what this Delve version understands.","triggerScenarios":"Evaluating a map in a Go 1.24+ binary whose hmap/swiss type, as parsed from DWARF, is missing fields Delve requires (e.g. dirPtr/dirLen or table fields absent) — immediately on the first map iteration step.","commonSituations":"Target built with a Go release whose swiss map struct layout changed while the installed Delve is older (or vice versa); unusual GOEXPERIMENT builds altering struct fields; binaries with incomplete DWARF for runtime types.","solutions":["Update Delve to the latest version (it tracks Go runtime layout changes closely)","Match the debugging environment: check 'go version <binary>' and install the Delve built for that Go release","If using a GOEXPERIMENT build, verify Delve supports that experiment (e.g. GOEXPERIMENT=mapsplitgroup) or rebuild without it"],"exampleFix":"// before\n$ dlv version\nDelve Debugger 1.21.0   # predates swiss maps\n// after\n$ go install github.com/go-delve/delve/cmd/dlv@latest\n$ dlv version\nDelve Debugger 1.24.x","handlingStrategy":"validation","validationCode":"// Precheck toolchain compatibility before debugging maps:\n//   $ go version ./mybinary   -> e.g. go1.24.1\n//   $ dlv version             -> must support that release's swiss map layout","typeGuard":null,"tryCatchPattern":"if strings.Contains(err.Error(), \"swiss table type does not have\") {\n    return fmt.Errorf(\"Delve too old for Go %s swiss maps: %w; upgrade delve\", goVer, err)\n}","preventionTips":["Install the latest Delve whenever you upgrade Go","Avoid GOEXPERIMENT map-layout experiments in debug builds","Keep stock toolchain binaries for debugging sessions"],"tags":["go","dwarf","maps","swiss-table","version-mismatch"],"backgroundTag":"swiss-map-iteration-failure","analyzedSha":"a23773e6c31361e43246bc43a424ee009679b174","analyzedAt":"2026-08-31T15:12:45.221Z","schemaVersion":2},"datasetVersion":"2026-08-31T19:17:28.585Z"}