How to fix Analytics: Code 2 - Event name invalid in Firebase

Check that your event name follows Firebase's naming requirements:
- Must start with an alphabetic character (a-z or A-Z)
- Can only contain alphanumeric characters and underscores
- Must be 1-40 characters long
- Cannot start with firebase_, google_, or ga_ prefixes

Example of valid event names:

user_signup
button_click
purchase_complete
form_submission
page_view

Example of INVALID event names:

1_user_signup          // Starts with number
_user_signup           // Starts with underscore
user-signup            // Contains hyphen
user signup            // Contains space
user.signup            // Contains period
firebase_custom_event  // Starts with reserved prefix
very_long_event_name_that_exceeds_the_character_limit_of_forty  // Too long

Once you've identified the invalid event name, update your code to use a compliant name. Replace the problematic event name with a valid one that meets Firebase's requirements.

For web (JavaScript):

// WRONG
firebase.analytics().logEvent("1st_purchase");

// CORRECT
firebase.analytics().logEvent("first_purchase");

For mobile (Swift):

// WRONG
Analytics.logEvent("user-login", parameters: [:])

// CORRECT
Analytics.logEvent("user_login", parameters: [:])

For mobile (Kotlin):

// WRONG
FirebaseAnalytics.getInstance(context).logEvent("purchase@checkout", null)

// CORRECT
FirebaseAnalytics.getInstance(context).logEvent("purchase_checkout", null)

After updating your code, test that the event logs successfully. Enable Firebase Analytics DebugView to monitor events in real-time.

For Android:

adb shell setprop debug.firebase.analytics.app com.example.myapp

For iOS, run your app in Xcode with -FIRAnalyticsDebugEnabled flag.

Once DebugView is enabled, trigger the event in your app and verify it appears in the Firebase Console under Analytics > DebugView. The event should appear with no error codes.

If your event name is valid but you're still seeing Code 2 errors, the problem might be in your custom parameters. Parameter names follow the same naming rules as event names:
- Must start with a letter
- Can contain alphanumeric characters and underscores only
- Must be 1-40 characters long
- Cannot use reserved prefixes

// Event name is valid, but parameter name has a hyphen
firebase.analytics().logEvent("user_login", {
  "login-method": "google"  // WRONG - hyphen not allowed
});

// Correct version
firebase.analytics().logEvent("user_login", {
  "login_method": "google"  // CORRECT
});