Are you unable to resolve the and have no will to go through a number of blogs to find out the solution? There is nothing to worry about as we are here to help you out with the easiest steps so that you can handle the problem that too without any technical knowledge.
Disable the password manager
The Protonmail doesn’t support all the password managers therefore you must disable it and enter the password manually. If this works for you then you can visit the official customer support and mail them about the bug describing the issue along with the system details so that they can look into it.
Use a different browser
If you are having issues with the present browser then you can check for updates and then try again. If you are using the latest version then you can use a different browser to see if it resolves the issue or not.
Clear the cache
You can visit the browser’s settings to get rid of the cache and cookies and then try again. At times clearing the clutter can help you to give that fresh start and you will be able to log in easily.