golang/go · error

action contains multiple PGO profile dependencies

Error message

action contains multiple PGO profile dependencies

What it means

When executing a build action, the go tool walks a.Deps for entries whose Mode is "preprocess PGO profile". At most one such dependency is expected per action; this fires when a second is found, indicating the action graph was constructed with duplicate PGO-profile dependencies. It is an internal invariant violation in the build-action planner, not caused by ordinary source or flag input.

Source

Thrown at src/cmd/go/internal/work/exec.go:844

		embed.Files = make(map[string]string)
		for _, file := range p.EmbedFiles {
			embed.Files[file] = fsys.Actual(filepath.Join(p.Dir, file))
		}
		js, err := json.MarshalIndent(&embed, "", "\t")
		if err != nil {
			return fmt.Errorf("marshal embedcfg: %v", err)
		}
		embedcfg = js
	}

	// Find PGO profile if needed.
	var pgoProfile string
	for _, a1 := range a.Deps {
		if a1.Mode != "preprocess PGO profile" {
			continue
		}
		if pgoProfile != "" {
			return fmt.Errorf("action contains multiple PGO profile dependencies")
		}
		pgoProfile = a1.built
	}

	var coverageConfig string
	if coverPr != nil {
		coverageConfig = coverPr.coverageConfig
	}

	if p.Internal.BuildInfo != nil && cfg.ModulesEnabled {
		prog := modload.ModInfoProg(p.Internal.BuildInfo.String(), cfg.BuildToolchainName == "gccgo")
		if len(prog) > 0 {
			if err := sh.writeFile(objdir+"_gomod_.go", prog); err != nil {
				return err
			}
			gofiles = append(gofiles, objdir+"_gomod_.go")
		}
	}

View on GitHub (pinned to b6b368adc5)

Solutions

1. Build with -pgo=off to confirm the issue is PGO-specific
2. Ensure the module has at most one default.pgo file (check the package directory and replace directives)
3. Report as a Go toolchain bug with the module layout and exact build flags

Example fix

// before
go build -pgo=auto ./...
// after (isolate the cause)
go build -pgo=off ./...

// Confirm at most one PGO profile before a -pgo build
matches, _ := filepath.Glob("*.pgo")
if len(matches) > 1 {
    return fmt.Errorf("multiple pgo files present: %v", matches)
}

When it happens

Trigger: Fires in (b *Builder).build inside the `for _, a1 := range a.Deps` loop when pgoProfile is already non-empty and another a1.Mode == "preprocess PGO profile" is encountered.

Common situations: Unusual combinations of -pgo flags, a module with multiple default.pgo files resolved by the loader, or a toolchain bug in action-graph construction. Very rare in normal PGO workflows.

Related errors

• vet config not found
• marshal embedcfg: %v
• internal error marshaling vet config: %v
• error reading profile header: %w
• internal error in windynrelocsym: redirect GOT token applied

AI-assisted analysis of golang/go@b6b368adc5 (2026-08-12). Data as JSON: /api/errors/cf491ac5a2f7e7b0. Report an issue: GitHub.