Today we released Yoroi Shelley Testnet extension 2.3.1
Bug fix: a small subset of users were unable to upgrade their wallet. This fixes the issue.
If you were affected, please try again.
Chrome download: https://chrome.google.com/webstore/detail/yoroi-shelley-testnet/bioklcnnnpdblghplkifbemcigeanmjn
Firefox download: https://addons.mozilla.org/en-US/firefox/addon/yoroi-shelley-testnet/