# go: module github.com/example/lib@v1.0.0: reading https://proxy.golang.org/github.com/example/lib/@v/v1.0.0.mod: 404 Not Found

- **ID:** `go/module-not-found-in-proxy`
- **Domain:** go
- **Category:** module_error
- **Verification:** ai_generated
- **Fix Rate:** 80%

## Root Cause

The module version does not exist on the Go module proxy, usually due to a typo in the module path or version tag not being pushed.

## Version Compatibility

| Version | Status | Introduced | Deprecated |
|---------|--------|------------|------------|
| 1.21 | active | — | — |
| 1.22 | active | — | — |
| 1.23 | active | — | — |

## Workarounds

1. **Verify the module path and version exist on the proxy or source repository.** (85% success)
   ```
   Run 'go list -m -versions github.com/example/lib' to see available versions. Check the repo tags.
   ```
2. **Use a direct source path with GOFLAGS=-mod=mod and replace directive.** (75% success)
   ```
   In go.mod, add: 'replace github.com/example/lib v1.0.0 => github.com/example/lib v1.0.1' (if version exists) or use a fork.
   ```

## Dead Ends

- **Using 'go get -u' to force update all modules.** — The targeted version doesn't exist, so updating won't fix the 404. (90% fail)
- **Adding the module path to go.sum manually.** — go.sum only stores checksums; it doesn't create module versions. (100% fail)