Redmine

Hi Team,

I tried to upgrade redmine version to 3.2.3 in ubuntu, nginx environment but I am getting below error (screenshot attached). And I tried to find the log for errors, but I am unable to find errors.

Please find the current redmine details :

Environment:
Redmine version 2.3.1.stable
Ruby version 2.1.0 (x86_64-linux)
Rails version 3.2.13
Environment production
Database adapter Mysql2

I had followed the below link to upgrade redmine

RedmineUpgrade

And also please specify any documentation to upgrade current redmine to latest stable version.