What causes "invalid section number in symbol table" in golang/go?

Verify PE integrity: `dumpbin /symbols ` or use a PE analysis tool to check for structural errors.

invalid section number in symbol table

Error message

invalid section number in symbol table

What it means

When parsing PE (Windows) symbol tables, each symbol references a section by its `SectionNumber`. After handling special cases (N_UNDEF, N_ABS, N_DEBUG), the code checks whether `SectionNumber` falls within the valid range [1, len(Sections)]. If it is negative or exceeds the number of sections in the file, this error fires, indicating a corrupt or malformed PE binary.

Source

Thrown at src/cmd/internal/objfile/pe.go:73

	var syms []Sym
	for _, s := range f.pe.Symbols {
		const (
			N_UNDEF = 0  // An undefined (extern) symbol
			N_ABS   = -1 // An absolute symbol (e_value is a constant, not an address)
			N_DEBUG = -2 // A debugging symbol
		)
		sym := Sym{Name: s.Name, Addr: uint64(s.Value), Code: '?'}
		switch s.SectionNumber {
		case N_UNDEF:
			sym.Code = 'U'
		case N_ABS:
			sym.Code = 'C'
		case N_DEBUG:
			sym.Code = '?'
		default:
			if s.SectionNumber < 0 || len(f.pe.Sections) < int(s.SectionNumber) {
				return nil, fmt.Errorf("invalid section number in symbol table")
			}
			sect := f.pe.Sections[s.SectionNumber-1]
			const (
				text  = 0x20
				data  = 0x40
				bss   = 0x80
				permW = 0x80000000
			)
			ch := sect.Characteristics
			switch {
			case ch&text != 0:
				sym.Code = 'T'
			case ch&data != 0:
				if ch&permW == 0 {
					sym.Code = 'R'
				} else if bssSectionNumber == s.SectionNumber && bssAddr > 0 && s.Value >= bssAddr {
					// Past runtime.bss is BSS.
					sym.Code = 'B'

View on GitHub (pinned to b6b368adc5)

Solutions

Verify PE integrity: `dumpbin /symbols <file>` or use a PE analysis tool to check for structural errors.
Rebuild the binary from source with a reliable linker.
If the binary was downloaded, re-download it to rule out truncation.
Use `pev` or similar PE forensics tools to assess the extent of corruption.

Example fix

// before — corrupt PE binary
f, err := objfile.Open("corrupt.exe")
_, err := f.Symbols()  // fails: invalid section number

// after — rebuild or re-download
$ go build -o app.exe ./...
f, err := objfile.Open("app.exe")
_, err := f.Symbols()  // succeeds

Defensive patterns

Strategy: validation

Validate before calling

// Validate PE symbol section numbers
func validatePESymbols(path string) error {
    f, err := pe.Open(path)
    if err != nil { return err }
    defer f.Close()
    for _, s := range f.Symbols {
        if s.SectionNumber > 0 && int(s.SectionNumber) > len(f.Sections) {
            return fmt.Errorf("corrupt PE: symbol %s references section %d (max %d)",
                s.Name, s.SectionNumber, len(f.Sections))
        }
    }
    return nil
}

Try / catch

syms, err := f.Symbols()
if err != nil && strings.Contains(err.Error(), "invalid section number") {
    return fmt.Errorf("corrupt PE binary — rebuild or re-download: %w", err)
}

Prevention

Verify PE structural integrity with dumpbin or pev before analysis.
Rebuild binaries from source when corruption is detected.
Use checksums to detect truncated or modified binaries.

When it happens

Trigger: Calling `objfile.Open` on a PE binary followed by `File.Symbols()`, where the PE symbol table contains an entry whose `SectionNumber` is out of range (negative or greater than the section count). This indicates the PE file is corrupt, was produced by a buggy tool, or was truncated.

Common situations: Analyzing a corrupt or partially-downloaded Windows `.exe` or `.dll`. Using a binary produced by a non-standard or buggy linker that wrote incorrect section numbers. Post-processing a PE file with a tool that corrupted the symbol table. Reading a PE file that was patched or hex-edited.

Related errors

AI-assisted analysis of golang/go@b6b368adc5 (2026-08-12). Data as JSON: /api/errors/afd3a4b8cf1ae0fa. Report an issue: GitHub.