What causes "reading srcfiles list: %w" in golang/go?

Run `go clean -cache` then rebuild

reading srcfiles list: %w

Error message

reading srcfiles list: %w

What it means

loadCachedSrcFiles reads the "srcfiles" subkey from the build cache, a newline-separated manifest of a cached action's source files. If cache.GetBytes fails, the error wraps the cause. This only fires on the cache-hit path, meaning the build believed a cached result existed but could not retrieve its source-file list.

Source

Thrown at src/cmd/go/internal/work/exec.go:1378

	}

	pr := &runCgoProvider{
		CFLAGS:                          replaceAll(cached.CFLAGS, "$OBJDIR/", a.Objdir),
		CXXFLAGS:                        replaceAll(cached.CXXFLAGS, "$OBJDIR/", a.Objdir),
		FFLAGS:                          replaceAll(cached.FFLAGS, "$OBJDIR/", a.Objdir),
		LDFLAGS:                         replaceAll(cached.LDFLAGS, "$OBJDIR/", a.Objdir),
		notCompatibleForInternalLinking: cached.NotCompatibleForInternalLinking,
		goFiles:                         goFilesObjdir,
	}

	return pr, nil
}

func (b *Builder) loadCachedSrcFiles(a *Action) ([]string, error) {
	c := cache.Default()
	list, _, err := cache.GetBytes(c, cache.Subkey(a.actionID, "srcfiles"))
	if err != nil {
		return nil, fmt.Errorf("reading srcfiles list: %w", err)
	}
	var srcfiles []string
	for name := range strings.SplitSeq(string(list), "\n") {
		if name == "" { // end of list
			continue
		}
		if strings.HasPrefix(name, "./") {
			srcfiles = append(srcfiles, name[2:])
			continue
		}
		if err := b.loadCachedObjdirFile(a, c, name); err != nil {
			return nil, err
		}
		srcfiles = append(srcfiles, a.Objdir+name)
	}
	return srcfiles, nil
}

View on GitHub (pinned to b6b368adc5)

Solutions

Run `go clean -cache` then rebuild
Move GOCACHE to a reliable local filesystem
Prevent concurrent processes from modifying the cache

Example fix

// before
go build ./...
// after
go clean -cache && go build ./...

Defensive patterns

Strategy: retry

Try / catch

// Treat srcfiles cache errors as recoverable: clean and rebuild
if bytes.Contains(out, []byte("reading srcfiles list")) {
    exec.Command("go", "clean", "-cache").Run()
    out, err = cmd.CombinedOutput()
}

Prevention

Keep GOCACHE on a reliable local filesystem
Do not run `go clean` during a build
Pin GOCACHE to a stable absolute path
Avoid sharing one cache across parallel CI jobs unless the cache is concurrency-safe

When it happens

Trigger: Fires in loadCachedSrcFiles when cache.GetBytes(c, cache.Subkey(a.actionID, "srcfiles")) errors, while vet or build reconstruction needs the source list of a cached package.

Common situations: Partially-written cache entries, GOCACHE on NFS/FUSE, concurrent cache writers, or `go clean` running in parallel with a build.

Related errors

AI-assisted analysis of golang/go@b6b368adc5 (2026-08-12). Data as JSON: /api/errors/d3c40c848a9552ae. Report an issue: GitHub.