What causes "context must be non-nil" in crowdsecurity/crowdsec?

Pass a valid context: use context.Background() or context.TODO() when no request-scoped context exists.

context must be non-nil

Error message

context must be non-nil

What it means

ApiClient.Do requires a context to attach to the outgoing HTTP request via req.WithContext(ctx). A nil context would make cancellation, deadlines and trace propagation impossible, so the client rejects it up front instead of failing obscurely inside net/http.

Source

Thrown at pkg/apiclient/client_http.go:76

	req, err := http.NewRequestWithContext(ctx, method, u.String(), buf)
	if err != nil {
		return nil, err
	}

	if body != nil {
		req.Header.Set("Content-Type", "application/json")
		if compressedBody {
			req.Header.Set("Content-Encoding", "gzip")
		}
	}

	return req, nil
}

func (c *ApiClient) Do(ctx context.Context, req *http.Request, v any) (*Response, error) {
	if ctx == nil {
		return nil, errors.New("context must be non-nil")
	}

	req = req.WithContext(ctx)

	// Check rate limit

	if c.UserAgent != "" {
		req.Header.Add("User-Agent", c.UserAgent)
	}

	log.Debugf("[URL] %s %s", req.Method, req.URL)

	resp, err := c.client.Do(req)
	if resp != nil && resp.Body != nil {
		defer resp.Body.Close()
	}

	if err != nil {

View on GitHub (pinned to 909b515798)

Solutions

Pass a valid context: use context.Background() or context.TODO() when no request-scoped context exists.
Pass the ctx received from an HTTP handler, command, or parent function instead of a stored nil field.
Add a nil-check/default at the call site wrapper before invoking Do.

Example fix

// before
var ctx context.Context
resp, err := client.Do(ctx, req, &result)
// after
ctx := context.Background()
resp, err := client.Do(ctx, req, &result)

Defensive patterns

Strategy: validation

Validate before calling

if ctx == nil {
    ctx = context.Background()
}
resp, err := client.Do(ctx, req, &result)

Type guard

func validCtx(ctx context.Context) context.Context {
    if ctx == nil {
        return context.Background()
    }
    return ctx
}

Try / catch

resp, err := client.Do(ctx, req, &out)
if err != nil {
    return fmt.Errorf("api call: %w", err)
}

Prevention

Never declare a context.Context without initializing it; always assign context.Background/TODO or a parent ctx.
Lint for nil-context params in HTTP client wrappers.
Thread ctx through function signatures instead of storing it in structs.

When it happens

Trigger: Calling Do(ctx, req, v) with a literally nil context.Context value, or with a variable that was declared as context.Context without initialization (zero value of an interface).

Common situations: Older code written before context was pervasive, wrappers that pass through a nil ctx field of a struct, tests that call Do(nil, ...) directly, refactors where a caller dropped ctx argument handling.

Related errors

AI-assisted analysis of crowdsecurity/crowdsec@909b515798 (2026-09-06). Data as JSON: /api/errors/f2580be1c5294446. Report an issue: GitHub.