Firebase 3 - We have blocked all requests from this device due to unusual activity

If you use Phone Authentication, Here is what to do:

1. Go to Firebase Console
2. Authentication ==> Sign-in-method
3. Go to "Phone" and pop-up will show
4. Add your phone number at "Phone Numbers for testing" along with a verification code from your choice.

And it works now :)

One of the possible solutions:

1. Go to your Firebase console -> Auth -> Users table

2. Locate the user you are testing.

3. Delete this user.

4. Retest.

I contacted firebase support and received this message:

The error "We have blocked all requests from this device due to unusual activity. Try again later." is usually thrown when a user is making SMS authentication requests to a certain number of times using the same phone number or IP address. These repeated requests are considered as a suspicious behavior which temporarily blocks the device or IP address.

Additionally, there's a limit of 5 SMS per phone number per 4 hours. With this, you may try doing the following to resolve the issue:

Reduce the frequency of attempts to avoid triggering the anti-abuse system Try using whitelisted phone numbers for testing your app Use multiple testing devices (as the limits are applied per IP or device) Wait for an hour for the quota to lift

I tried to increase the quota as per @lhk answer but there answer is the following:

You also mentioned that you have increased the quota to 1000 but it didn't work. Do note that this "Manage to sign up quota" field is intended for Email/Password and Anonymous sign-ups.