Fix FileServeError: open static/assets/logo.png: no such file or directory in Echo

This error occurs when Echo's static file handler cannot find the requested file at the specified filesystem path, typically because the working directory differs between development and production or the static file path is relative. Fix it by using embed.FS for production builds or configuring an absolute path to the static directory.

Reading the Stack Trace

Here's what each line means:

• os.Open({0x1028f1e60, 0x1a}): The OS-level Open call fails because the file path resolves to a non-existent location on disk.
• github.com/labstack/echo/v4.(*Echo).Static.func1({0x1029e4f80, 0x14000226000}): Echo's static file handler tries to open the requested file relative to the configured static directory root.
• os.(*File).openFile(0x0, {0x1028f1e60, 0x1a}, 0x0, 0x0): The file open operation returns an error because the file does not exist at the resolved path.

Common Causes

func main() {
	e := echo.New()
	e.Static("/static", "static/assets") // relative path
	e.Start(":8080")
}

# Dockerfile
FROM golang:1.22 AS builder
COPY . .
RUN go build -o app

FROM alpine
COPY --from=builder /app/app /app
# Missing: COPY --from=builder /app/static /static
CMD ["/app"]

e.Static("/files", "./uploads") // no path sanitization

The Fix

Use Go's embed package to bundle static files into the binary. This eliminates path resolution issues across environments and ensures files are always available regardless of the working directory or container layout.

func main() {
	e := echo.New()
	e.Static("/static", "static/assets")
	e.Start(":8080")
}

//go:embed static/assets/*
var staticFS embed.FS

func main() {
	e := echo.New()

	contentFS, err := fs.Sub(staticFS, "static/assets")
	if err != nil {
		log.Fatal(err)
	}
	assetHandler := http.FileServer(http.FS(contentFS))
	e.GET("/static/*", echo.WrapHandler(http.StripPrefix("/static/", assetHandler)))

	e.Start(":8080")
}

Testing the Fix

package main_test

import (
	"net/http"
	"net/http/httptest"
	"testing"

	"github.com/labstack/echo/v4"
	"github.com/stretchr/testify/assert"
)

func TestStaticFile_Exists(t *testing.T) {
	e := setupEchoWithStatic()

	req := httptest.NewRequest(http.MethodGet, "/static/logo.png", nil)
	rec := httptest.NewRecorder()
	e.ServeHTTP(rec, req)

	assert.Equal(t, http.StatusOK, rec.Code)
}

func TestStaticFile_NotFound(t *testing.T) {
	e := setupEchoWithStatic()

	req := httptest.NewRequest(http.MethodGet, "/static/nonexistent.png", nil)
	rec := httptest.NewRecorder()
	e.ServeHTTP(rec, req)

	assert.Equal(t, http.StatusNotFound, rec.Code)
}

Run your tests:

go test ./... -v

Pushing Through CI/CD

git checkout -b fix/echo-file-serve-error,git add main.go,git commit -m "fix: embed static assets to avoid file path resolution issues",git push origin fix/echo-file-serve-error

Your CI config should look something like this:

name: CI
on:
  pull_request:
    branches: [main]
jobs:
  test:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: actions/setup-go@v5
        with:
          go-version: '1.22'
      - run: go mod download
      - run: go vet ./...
      - run: go test ./... -race -coverprofile=coverage.out
      - run: go build ./...

The Full Manual Process: 18 Steps

Here's every step you just went through to fix this one bug:

1. Notice the error alert or see it in your monitoring tool
2. Open the error dashboard and read the stack trace
3. Identify the file and line number from the stack trace
4. Open your IDE and navigate to the file
5. Read the surrounding code to understand context
6. Reproduce the error locally
7. Identify the root cause
8. Write the fix
9. Run the test suite locally
10. Fix any failing tests
11. Write new tests covering the edge case
12. Run the full test suite again
13. Create a new git branch
14. Commit and push your changes
15. Open a pull request
16. Wait for code review
17. Merge and deploy to production
18. Monitor production to confirm the error is resolved

Total time: 30-60 minutes. For one bug.

go get github.com/bugstack/sdk

import "github.com/bugstack/sdk"

func init() {
  bugstack.Init(os.Getenv("BUGSTACK_API_KEY"))
}

Deploying the Fix (Manual Path)

1. Run go test ./... locally to confirm static files are served.
2. Open a pull request with the embed changes.
3. Wait for CI checks to pass on the PR.
4. Have a teammate review and approve the PR.
5. Merge to main and verify static assets load in staging.

Frequently Asked Questions