golang/go · error

fetching %s: %v

Error message

fetching %s: %v

What it means

Inside metaImportsForPrefix (the cached prefix-verification fetch), web.Get failed. The result is cached via setCache for the process lifetime. The %s is the import prefix; %v is the transport error.

Source

Thrown at src/cmd/go/internal/vcs/vcs.go:1152

		fetchCache[importPrefix] = res
		return res, nil
	}

	resi, _, _ := fetchGroup.Do(importPrefix, func() (resi any, err error) {
		fetchCacheMu.Lock()
		if res, ok := fetchCache[importPrefix]; ok {
			fetchCacheMu.Unlock()
			return res, nil
		}
		fetchCacheMu.Unlock()

		url, err := urlForImportPath(importPrefix)
		if err != nil {
			return setCache(fetchResult{err: err})
		}
		resp, err := web.Get(security, url)
		if err != nil {
			return setCache(fetchResult{url: url, err: fmt.Errorf("fetching %s: %v", importPrefix, err)})
		}
		body := resp.Body
		defer body.Close()
		imports, err := parseMetaGoImports(body, mod)
		if len(imports) == 0 {
			if respErr := resp.Err(); respErr != nil {
				// If the server's status was not OK, prefer to report that instead of
				// an XML parse error.
				return setCache(fetchResult{url: url, err: respErr})
			}
		}
		if err != nil {
			return setCache(fetchResult{url: url, err: fmt.Errorf("parsing %s: %v", resp.URL, err)})
		}
		if len(imports) == 0 {
			err = fmt.Errorf("fetching %s: no go-import meta tag found in %s", importPrefix, resp.URL)
		}
		return setCache(fetchResult{url: url, imports: imports, err: err})

View on GitHub (pinned to b6b368adc5)

Solutions

1. Retry (the cached failure is only process-scoped)
2. Verify the prefix host is reachable and serves go-import tags
3. Clear module cache lock files and re-run; check GOPROXY/GONOSUMDB

When it happens

Trigger: Secondary verification fetch for a non-authoritative prefix fails, OR the initial fetch in the prefix-resolution path fails — same transport-level causes as 1140 but on the prefix host.

Common situations: Transient network errors during prefix verification; the prefix host differs from the import host and is unreachable; CDN flakiness.

Related errors

• https fetch: %v
• ReadZip: encoded file exceeds allowed size
• parsing %s: %v
• parse %s: %v
• parse %s: no go-import meta tags (%s)

AI-assisted analysis of golang/go@b6b368adc5 (2026-08-12). Data as JSON: /api/errors/cf29c33170b0077a. Report an issue: GitHub.