Serialization error – AARP Now Review

If I try to login to the app beyond the initial download on either the iPone or the iPad, the existing password is unrecognized. Error message is “Confirmation failed. Response serialization error (The data couldn’t be read because it isn’t in the correct format.)”. Issue started after only the last app update. Work around is to delete and reinstall app, but that only works once.
Review by decline-to-state on AARP Now.