Update fail 2.5 to 2.8

I have tried to update the app from version 2.5 to version 2.8 through CPANEL and once the installation is finished I can not access the client portal or the admin portal. The following error appears on both pages:

“Whoops, looks like something went wrong.” Any solution? If it is necessary to make a new installation since version 2.8, how can I recover my installation code? I made the purchase several years ago and I do not find the installation code for CPANEL.

Thanks for your attention.

Please load /update or (/public/update) in your browser and check for an error.