Login to your Gmail account and click on the circle with your initial on it placed at the top-right corner. Click on My Account next to open your account’s settings. Click on Sign-in & Security to open those settings. To fix Gmail authentication failed, you must determine the level of security you need. Click on 2-factor authentication to setup the two-factor authentication on your account. The major reason for when this security measure fails is wrong username or password that the user is inserting. So, it would be best to recheck and insert the correct credentials.
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