We’re in the final stretch of the migration from getpersonas.com to AMO! On Thursday, 3/28 at approximately 2pm PDT, getpersonas.com will become read-only—this means you won’t be able to create an account or log in. It also means you won’t be able to submit any new themes until the migration is complete, in about 1-2 weeks.
Once the migration is done, traffic to getpersonas.com will be redirected to addons.mozilla.org/firefox/themes/, and you will be able to create accounts, log in, and submit new themes from there.
Thanks for your patience and understanding!