Upgrade "rancher" failed: could not get information about the resource: conversion webhook for cert-manager.io/v1

Hi,

I’m trying to upgrade rancher, but get this error:

upgrade.go:431: [debug] warning: Upgrade "rancher" failed: could not get information about the resource: conversion webhook for cert-manager.io/v1, Kind=Issuer failed: Post "https://cert-manager-webhook.cert-manager.svc:443/convert?timeout=30s": service "cert-manager-webhook" not found
Error: UPGRADE FAILED: could not get information about the resource: conversion webhook for cert-manager.io/v1, Kind=Issuer failed: Post "https://cert-manager-webhook.cert-manager.svc:443/convert?timeout=30s": service "cert-manager-webhook" not found
helm.go:84: [debug] conversion webhook for cert-manager.io/v1, Kind=Issuer failed: Post "https://cert-manager-webhook.cert-manager.svc:443/convert?timeout=30s": service "cert-manager-webhook" not found

I previously had cert-manager installed but then removed it, as it is not required when using certificates from files (described here).

I uninstalled cert-manager, but somewhere still seems to be something which links to cert-manager-webhook.

Where is that configuration located, so I can disable/remove that?

Update: Got one step further with this manual.

kubectl delete -f https://github.com/cert-manager/cert-manager/releases/download/v1.5.1/cert-manager.crds.yaml

New error:

Error: UPGRADE FAILED: unable to recognize "": no matches for kind "Issuer" in version "cert-manager.io/v1"
helm.go:84: [debug] unable to recognize "": no matches for kind "Issuer" in version "cert-manager.io/v1"
UPGRADE FAILED

Best regards,
Markus