Error updateting by snap

Error updating by snap
I have mounted a server with ubuntu 16 with nextcloud, I installed it using snap.
To update from the 14th to the 15th use the command by terminal
sudo apt update && sudo apt upgrade
sudo snap refresh
I check if everything ends well
sudo snap list
Name Version Rev Tracking Publisher Notes
core 16-2.37.4 6531 stable canonical * core
nextcloud 15.0.5snap1 11891 stable nextcloud * -
The problem is that the website tells me
Update needed
Use the command line updater because it has an instance with more than 50 users.

For help, consult the documentation.
When I update through the web
The following error occurs
Upgrade to 15.0.5
Exception: Updates between multiple major versions and downgrades are unsupported.

Detailed records
The update had a problem. For more information see our forum article to fix this problem.

snap list --all
Name Version Rev Tracking Publisher Notes
core 16-2.35 5328 stable canonical* core,disabled
core 16-2.37.4 6531 stable canonical* core
nextcloud 13.0.6snap1 8971 stable nextcloud* disabled
nextcloud 15.0.5snap1 11891 stable nextcloud* -