{"record":{"id":"3be6b5b7ff561ca5","repo":"go-delve/delve","slug":"invalid-interface-type","errorCode":null,"errorMessage":"invalid interface type","messagePattern":"invalid interface type","errorType":"exception","errorClass":null,"httpStatus":null,"severity":"error","filePath":"pkg/proc/variables.go","lineNumber":2120,"sourceCode":"\t}\n\treturn\n}\n\nfunc (v *Variable) loadInterface(recurseLevel int, loadData bool, cfg LoadConfig) {\n\t_type, data, isnil := v.readInterface()\n\n\tif isnil {\n\t\t// interface to nil\n\t\tdata = data.maybeDereference()\n\t\tv.Children = []Variable{*data}\n\t\tif loadData {\n\t\t\tv.Children[0].loadValueInternal(recurseLevel, cfg)\n\t\t}\n\t\treturn\n\t}\n\n\tif data == nil {\n\t\tv.Unreadable = errors.New(\"invalid interface type\")\n\t\treturn\n\t}\n\n\tmds, err := _type.bi.getModuleData(_type.mem)\n\tif err != nil {\n\t\tv.Unreadable = fmt.Errorf(\"error loading module data: %v\", err)\n\t\treturn\n\t}\n\n\ttyp, directIface, err := RuntimeTypeToDIE(_type, data.Addr, mds)\n\tif err != nil {\n\t\tv.Unreadable = err\n\t\treturn\n\t}\n\n\tderef := false\n\tif !directIface {\n\t\trealtyp := godwarf.ResolveTypedef(typ)","sourceCodeStart":2102,"sourceCodeEnd":2138,"githubUrl":"https://github.com/go-delve/delve/blob/a23773e6c31361e43246bc43a424ee009679b174/pkg/proc/variables.go#L2102-L2138","documentation":"Thrown while loading an interface-typed variable (in the Go runtime itab/eface handling path) when the concrete type's data pointer is nil even though a type was expected, or in the module-data path when the type descriptor cannot be resolved. Delve refuses to fabricate a value, so the variable is marked unreadable with this message.","triggerScenarios":"Evaluating an interface variable whose type word resolved but whose data pointer read as nil; loading interface contents during interface type resolution (_type) when the underlying runtime type structure could not be found in memory.","commonSituations":"Inspecting partially initialized interfaces before assignment; corrupted or mismatched runtime type metadata (binary built with a Go version Delve doesn't fully support); reading freed/zeroed memory after the process state changed.","solutions":["Print the variable with a lower recursion depth or use 'print <var>' after the interface is fully assigned","Verify the binary being debugged matches the sources (rebuild to avoid stale metadata)","Upgrade Delve to match the Go version of the target binary","Inspect the concrete value via 'print <expr>.(type)' style narrowing in your code before debugging"],"exampleFix":"// before: evaluating an interface before initialization\nvar w io.Writer // nil data on some type words\n// after: initialize before inspecting\nvar w io.Writer = os.Stdout","handlingStrategy":"type-guard","validationCode":"// Check the interface is fully initialized before evaluating\nif ifaceVar.DwarfType == nil || ifaceVar.Addr == 0 {\n    return errors.New(\"interface not initialized; skip evaluation\")\n}","typeGuard":"func isConcreteInterface(v *proc.Variable) bool {\n    return v.Kind == reflect.Interface && v.Children != nil && len(v.Children) > 0 && v.Children[0].Addr != 0\n}","tryCatchPattern":"v, err := loadInterface(expr)\nif err != nil && strings.Contains(err.Error(), \"invalid interface type\") {\n    // inspect raw type word instead\ntw, _ := readUintptr(ifaceVar.Addr)\n    fmt.Printf(\"interface data nil; type word=%x\\n\", tw)\n}","preventionTips":["Initialize interfaces before inspecting them at breakpoints","Ensure the debugged binary matches your sources and Go version","Upgrade Delve for newer Go runtime type metadata","Reduce recursion depth when evaluating deeply nested interfaces"],"tags":["debugger","go","interface","dwarf"],"backgroundTag":"invalid-interface-type","analyzedSha":"a23773e6c31361e43246bc43a424ee009679b174","analyzedAt":"2026-08-31T15:12:45.221Z","schemaVersion":2},"datasetVersion":"2026-08-31T19:17:28.585Z"}