cd/docs/operator-manual/upgrading/1.5-1.6.md

v1.5 to 1.6

Removed Deprecated Field of /managed-resources API

The deprecated diff field had been removed from /api/v1/applications/<app-name>/managed-resources API. The field is not used by Argo CD CLI or UI, so it might affect you only if you programmatically use the managed-resources API.

From here on you can follow the regular upgrade process.