If your Gmail app prevents you from logging in on your iPhone, there’s no need to panic. There are a few things that can cause this. Also, you can solve this problem easily. Here are a few things you can do to solve iPhone Gmail login issues:
CHECK ALERTS BY GOING TO GMAIL SITE
When you try to sign in to your account with a new phone, Google could block the attempt. In this case, it is assumed that it was a hacking attempt. The Gmail app won’t tell you why it’s suddenly not working, obviously. So, log in to your Gmail account using your browser. Check for a message saying “We blocked a sign-in”. Click on “That was me”, or “Review devices now” to fix this issue.
REVIEW RECENT DEVICES ON YOUR ACCOUNT
On the web version of your Gmail, go to Device Activity & Notifications, under My Account. Check the devices from which your email was accessed and unblock the ones that you used. After that, you will be allowed to sign in.
PERFORM CAPTCHA RESET
This unlocks the security features temporarily, so you can connect a new device to your Gmail. Visit Google’s CAPTCHA reset page to do this. Sign in with your username and password. After doing that, try to sign in to your Gmail account with your iPhone or iPad. Google will remember this device from now on, so there will not be any iPhone Gmail login issues in future.
DELETE GMAIL ACCOUNT FROM IPHONE AND ADD AGAIN
Sometimes, there might be a problem with your account. In this case, you should delete the account from your iPhone and add it back. Your emails are stored on Gmail servers, so you can always get them back. To remove Gmail from your iPhone, go to Settings > Mail, Contacts, Calendars > Gmail > Delete Account > Delete from my iPhone. To add it back, go to Settings > Mail, Contacts, Calendars, tap on Add Account, tap on Google, and enter your details.
Note: Make sure you are not using the mail delivery system known as POP, as it deletes emails from the server. Check your emails on the web version of Gmail to be sure that they are still there before you delete your account. Hopefully, this should solve your iPhone Gmail issues.