(please specify the website or account you are asking about)
(please share the FULL error message you see)
Everything was working when I did the setup as a sub-domain (waiting for my domain to be pointed over). However I couldn’t move the website to my addon domain. I backed up the website, deleted the account and started again with the correct domain name setup as addon. I’ve reloaded the backup using FTP and in Softaculous I’ve initiated WordPress but wp-admin doesn’t work, the webpage is not been seen and I can’t see any way to install from backup.
(other information and details relevant to your question)