Regarding updation

Hi,

while I am updating from 6.3.4 to 6.3.5 or any old to new version Iam getting home page like this. An icon is rotating there and its showing message as "Upgrade in progress
Only admin user can connect.".But when I keep it for more than 1hour the message is like that only, I have in dailoma that is it updated to new version or not.It is not showing success message if i kept it for nearly 2 hours.When I refreshed the page i came to see success message database updated.But when I looked into some parts iam getting error while accessing the data.How to solve this issue.
PFA:


Note: We have around 20 activities,10 risks, 10 issues.How much time it takes to upgrade from old version to new.