{"record":{"id":"1ee77e62385be8a0","repo":"go-delve/delve","slug":"could-not-load-swiss-table-groups-data-v","errorCode":null,"errorMessage":"could not load swiss table groups data: %v","messagePattern":"could not load swiss table groups data: (.+?)","errorType":"exception","errorClass":null,"httpStatus":null,"severity":"error","filePath":"pkg/proc/mapiter.go","lineNumber":629,"sourceCode":"\tfield, err2 := tab.toField(it.tableFieldIndex)\n\tif err2 != nil {\n\t\tit.v.Unreadable = fmt.Errorf(\"could not load swiss table index field: %v\", err2)\n\t\treturn\n\t}\n\tr.index, err = field.asInt()\n\tif err != nil {\n\t\tit.v.Unreadable = fmt.Errorf(\"could not load swiss table index: %v\", err)\n\t\treturn\n\t}\n\n\tgroups, err2 := tab.toField(it.tableFieldGroups)\n\tif err2 != nil {\n\t\tit.v.Unreadable = fmt.Errorf(\"could not load swiss table groups field: %v\", err2)\n\t\treturn\n\t}\n\tr.groups, err2 = groups.toField(it.groupsFieldData)\n\tif err2 != nil {\n\t\tit.v.Unreadable = fmt.Errorf(\"could not load swiss table groups data: %v\", err2)\n\t\treturn\n\t}\n\n\tfield, err2 = groups.toField(it.groupsFieldLengthMask)\n\tif err2 != nil {\n\t\tit.v.Unreadable = fmt.Errorf(\"could not load swiss table groups lengthMask field: %v\", err2)\n\t\treturn\n\t}\n\tgroupsLengthMask, err := field.asUint()\n\tif err != nil {\n\t\tit.v.Unreadable = fmt.Errorf(\"could not load swiss table group lengthMask: %v\", err)\n\t\treturn\n\t}\n\n\t// convert the type of groups from *group to *[len]group so that it's easier to use\n\tr.groups.DwarfType = pointerTo(fakeArrayType(groupsLengthMask+1, it.groupType), it.v.bi.Arch)\n\tr.groups.RealType = r.groups.DwarfType\n\tr.groups = r.groups.maybeDereference()","sourceCodeStart":611,"sourceCodeEnd":647,"githubUrl":"https://github.com/go-delve/delve/blob/a23773e6c31361e43246bc43a424ee009679b174/pkg/proc/mapiter.go#L611-L647","documentation":"Set on a map Variable while Delve drills into the groups field of a swiss map table: after fetching the 'groups' struct field it dereferences it to the inner maps.groups (old/new) struct and reads its 'data' field. Failure means the nested field could not be resolved from DWARF or read from target memory. Delve throws it because the actual group array pointer cannot be located without this field.","triggerScenarios":"Iterating a swiss map whose maps.groups struct lacks a readable 'data' field in debug info, or whose groups pointer points to unreadable memory (e.g. freed/corrupted table).","commonSituations":"Go runtime internals changed between versions (groups union layout); inspecting stale heap memory of a live mutating map during aggressive GC; binaries built with mismatched toolchain/Delve combination.","solutions":["Upgrade Delve to the latest release supporting your Go version","Rebuild the binary with the supported Go toolchain and full DWARF","Re-inspect the map while the process is stopped at a stable breakpoint (avoid stale reads after mutation)","If debugging a core dump, ensure the dump was taken with a compatible Go/Delve pair"],"exampleFix":null,"handlingStrategy":"type-guard","validationCode":"if v == nil || v.Unreadable != nil { return } // stale or unreadable map variable; re-evaluate at breakpoint","typeGuard":"func fresh(v *proc.Variable) bool { return v != nil && v.Unreadable == nil }","tryCatchPattern":"if err := v.Unreadable; err != nil { reevaluateAtBreakpoint(); return }","preventionTips":["Re-evaluate map variables at each breakpoint rather than caching them across resumes","Keep Go toolchain and Delve versions aligned","Use full core dumps so group memory is readable","Avoid inspecting maps while the target runs asynchronously"],"tags":["go","debugger","dwarf","swiss-map","memory"],"backgroundTag":"swiss-map-layout-mismatch","analyzedSha":"a23773e6c31361e43246bc43a424ee009679b174","analyzedAt":"2026-08-31T15:12:45.221Z","schemaVersion":2},"datasetVersion":"2026-08-31T19:17:28.585Z"}