TP-Link / Kasa device broken after 2026.4.0

After upgarding to 2026.4.0 my Kasa power strip is disconnected. I get a prompt that says “Authentication expired” to put my login info again but it doesn’t work with the below error - the login info works fine on https://www.tplinkcloud.com/admin.php

“Unable to authenticate: Device response did not match our challenge on ip 192.168.86.29, check that your e-mail and password (both case-sensitive) are correct.”

I have in the past had a similar problem with their smart plugs Something to do with the fact that these devices share passwords between themselves. I had to turn off ALL the other devices then re-add the offending device. It then accepted the password. Embarrassingly it is mentioned in the installation instructions Hope this your problem as it is an easy fix.

All my other devices were off when I tried to add it, do I need to unplug everything too?

They need to be powered off so either wall switch off or unplugged

Yup, unplugging everything, resetting the device, and rebooting HA worked

That’s good to hear!