Please make sure you have added the correct repository for the stable/11 release: https://docs.openproject.org/installation-and-operations/installation/packaged/

Thanks for your help.

In order to be sure not to make an error (we have all our projects on proxmox), please confirm that I must apply the following procedure:

Import the PGP key:

wget -qO- https://dl.packager.io/srv/opf/openproject/key | sudo apt-key add -

Add the OpenProject package source:

sudo wget -O /etc/apt/sources.list.d/openproject.list \

  https://dl.packager.io/srv/opf/openproject/stable/11/installer/ubuntu/18.04.repo

Download the OpenProject package:

sudo apt-get update

sudo apt-get install --only-upgrade openproject

sudo openproject configure

Yes, you can add -s to your apt-get install command to do a dry-run

what do you mean by "dry run" please ?

English is not my native language ;-)

apt-get install -s option will display the action it will perform, without really performing it. Remove the -s flag when you have confirmed it will install the correct version.

ok so thank you for testing I just have to do:

sudo apt-get install -s --only-upgrade openproject

Yes

thank you

another question, why didn't I have to do this for previous updates?

Because (I suppose) you started with 10.x and you only upgraded to 10.y versions, while 11 is a major release, hence why you need to switch your repository details.

yes exactly

update done thank you for your help

yes exactly

update done thank you for your help