1. have a compute resource with wrong fingerprint, to reproduce, you can do this in console

ComputeResource.find_by(name: 'myawesome-cr').update(:pubkey_hash => 'bla')

2. go to edit page of the compute resource

3. get 500 with:

app/helpers/compute_resources_helper.rb:70:in `rescue in list_datacenters'
app/helpers/compute_resources_helper.rb:67:in `list_datacenters'
app/views/compute_resources/form/_vmware.html.erb:4:in `_0cdfc47759cf3a147931acb8b27f0140'
app/views/compute_resources/_form.html.erb:21:in `block in _723f7b053c2578fe9230905160343f4a'
app/helpers/form_helper.rb:296:in `form_for'
app/views/compute_resources/_form.html.erb:1:in `_723f7b053c2578fe9230905160343f4a'
app/views/compute_resources/edit.html.erb:3:in `_eaa4de733251f98201fdd715a20f2ef0'
app/controllers/concerns/application_shared.rb:15:in `set_timezone'
app/models/concerns/foreman/thread_session.rb:32:in `clear_thread'
app/controllers/concerns/foreman/controller/topbar_sweeper.rb:12:in `set_topbar_sweeper_controller'
lib/middleware/telemetry.rb:9:in `call'
lib/middleware/catch_json_parse_errors.rb:8:in `call'

The error causing this is:

ERF56-4248 [Foreman::FingerprintException]: The remote system presented a public key with hash d017b8e1a47874e3c5851981ebb97638b3a5cc09a0c79554352d3a20f9065544 but we're expecting a different hash. If you are sure the remote system is authentic, go to the compute resource edit page, press the 'Test Connection' or 'Load Datacenters' button and submit