Attachments are not working after upgrading redmine and agile plugin

Hi,

I'm facing an issue that the attachments are not working after upgrading the redmine server and agile plugin.

Please find the details below:

Old:
Redmine : 3.0.1
Agile plugin : 1.4.2

Upgraded:

Redmine : 3.4.2
Agile plugin : 1.4.4

After upgrading both redmine server and agile plugin , the attachments are not view-able.

Please find the below error, whenever an attachement is clicked to view.

"The page you were trying to access doesn't exist or has been removed."

Please let me know on how to get rid of this issue.

Thanks,
Sathish

Redmine