Usually if you clear cache and cookies then reboot your computer it'll fix the log-in loop. If you happen to be using IE as a browser switch to Firefox or Chrome.

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I had a similar problem when I changed my password in Chrome.

What worked for me was immediately after the error message came up to click on 'Sign in' immediately, without retyping anything. It would then go through as normal.

Some general tips regarding sign-in issues can be found here:

https://community.ebay.com.au/t5/Technical-Issues/Difficulty-logging-in/m-p/2336326#M5054

When that happens to me, I manually type in the password and it works.

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