Update to latest minor version

First you need to upgrade Nextcloud to the latest minor version of Nextcloud. When that’s done, you can upgrade to the newest major version.

Prepare apps for latest version

Before you upgrade to a new major version, you need to make the following changes to your appinfo/info.xml to allow the next version of Nextcloud for all of your apps. So for Nextcloud 26 you need the following changes to the file:

<dependencies>
    <nextcloud min-version="23" max-version="26" />
</dependencies>

To make the changes to all apps at the same time you could go to the root of your Nextcloud installation and run the following command:

sed -i -e 's/max-version="25"/max-version="26"/' apps/*/appinfo/info.xml

Here you can just change 26 to the newer version of Nextcloud.

Upgrade to latest major version

After this you can go back to the web interface and update to the latest major version of Nextcloud.

Read more over at Nextcloud!