Ondrej, could you please take a quick look if this is that same as BZ 1595120 and the same fix helps? Or does this needs to be fixed in host form so that we don't display compute resources unavailable in org/loc combination selected for the host?

Created redmine issue http://projects.theforeman.org/issues/24348 from this bug

This is something different, cloning upstream.

Build: Satellite 6.4.0 snap22

I am still able to re-produce the error.
All the entities are in Default org and location, expect the Compute resource which is in ORG "abc"

hammer> compute-resource info --id 4
Id:            4
Name:          sjagtap_libvirt
Provider:      Libvirt
Url:           qemu+tcp://<libvirt>/system
Description:   
User:          
Locations:     
    Default Location
Organizations: 
    Default Organization
Created at:    2018/09/20 12:26:38
Updated at:    2018/09/20 12:26:38

hammer> host create --name host1 --architecture-id=1 --compute-resource-id=4 --domain-id=1 --environment-id=1 --ip="148.172.224.43" --location-id="2" --mac="94:e3:d9:06:72:48" --medium-id="1" --operatingsystem-id=3 --organization-id="1" --partition-table-id=94 --puppet-proxy-id="1" --root-password=dog8code
Host created.

compute-resource update --id 4 --organizations abc
Compute resource updated.
hammer> compute-resource info --id 4
Id:            4
Name:          sjagtap_libvirt
Provider:      Libvirt
Url:           qemu+tcp://<libvirt>/system
Description:   
User:          
Locations:     
    Default Location
Organizations: 
    abc
Created at:    2018/09/20 12:26:38
Updated at:    2018/09/20 12:26:38


hammer -v host create --name host2 --architecture-id=1 --compute-resource-id=4 --domain-id=1 --environment-id=1 --ip="148.172.224.43" --location-id="2" --mac="94:e3:d9:06:72:48" --medium-id="1" --operatingsystem-id=3 --organization-id="1" --partition-table-id=94 --puppet-proxy-id="1" --root-password=dog8code
[ERROR 2018-09-20T08:30:45 API] 500 Internal Server Error
[ERROR 2018-09-20T08:30:45 Exception] Internal Server Error: the server was unable to finish the request. This may be caused by unavailability of some required service, incorrect API call or a server-side bug. There may be more information in the server's logs.
Could not create the host:
  Internal Server Error: the server was unable to finish the request. This may be caused by unavailability of some required service, incorrect API call or a server-side bug. There may be more information in the server's logs.
[ERROR 2018-09-20T08:30:45 Exception] 

RestClient::InternalServerError (500 Internal Server Error):
    /opt/theforeman/tfm/root/usr/share/gems/gems/rest-client-2.0.1/lib/restclient/abstract_response.rb:223:in `exception_with_response'
    /opt/theforeman/tfm/root/usr/share/gems/gems/rest-client-2.0.1/lib/restclient/abstract_response.rb:103:in `return!'
    /opt/theforeman/tfm/root/usr/share/gems/gems/apipie-bindings-0.2.2/lib/apipie_bindings/api.rb:353:in `block in rest_client_call_block'
    /opt/theforeman/tfm/root/usr/share/gems/gems/rest-client-2.0.1/lib/restclient/request.rb:807:in `process_result'
    /opt/theforeman/tfm/root/usr/share/gems/gems/rest-client-2.0.1/lib/restclient/request.rb:725:in `block in transmit'
    /opt/rh/rh-ruby24/root/usr/share/ruby/net/http.rb:877:in `start'
    /opt/theforeman/tfm/root/usr/share/gems/gems/rest-client-2.0.1/lib/restclient/request.rb:715:in `transmit'
    /opt/theforeman/tfm/root/usr/share/gems/gems/rest-client-2.0.1/lib/restclient/request.rb:145:in `execute'
    /opt/theforeman/tfm/root/usr/share/gems/gems/rest-client-2.0.1/lib/restclient/request.rb:52:in `execute'
    /opt/theforeman/tfm/root/usr/share/gems/gems/rest-client-2.0.1/lib/restclient/resource.rb:67:in `post'
    /opt/theforeman/tfm/root/usr/share/gems/gems/apipie-bindings-0.2.2/lib/apipie_bindings/api.rb:327:in `call_client'
    /opt/theforeman/tfm/root/usr/share/gems/gems/apipie-bindings-0.2.2/lib/apipie_bindings/api.rb:240:in `http_call'
    /opt/theforeman/tfm/root/usr/share/gems/gems/apipie-bindings-0.2.2/lib/apipie_bindings/api.rb:190:in `call_action'
    /opt/theforeman/tfm/root/usr/share/gems/gems/apipie-bindings-0.2.2/lib/apipie_bindings/api.rb:185:in `call'
    /opt/theforeman/tfm/root/usr/share/gems/gems/apipie-bindings-0.2.2/lib/apipie_bindings/resource.rb:21:in `call'
    /opt/theforeman/tfm/root/usr/share/gems/gems/hammer_cli-0.13.1/lib/hammer_cli/apipie/command.rb:51:in `send_request'
    /opt/theforeman/tfm/root/usr/share/gems/gems/hammer_cli_foreman-0.13.2/lib/hammer_cli_foreman/commands.rb:168:in `send_request'
    /opt/theforeman/tfm/root/usr/share/gems/gems/hammer_cli-0.13.1/lib/hammer_cli/apipie/command.rb:34:in `execute'
    /opt/theforeman/tfm/root/usr/share/gems/gems/clamp-1.1.2/lib/clamp/command.rb:63:in `run'
    /opt/theforeman/tfm/root/usr/share/gems/gems/hammer_cli-0.13.1/lib/hammer_cli/abstract.rb:29:in `run'
    /opt/theforeman/tfm/root/usr/share/gems/gems/clamp-1.1.2/lib/clamp/subcommand/execution.rb:11:in `execute'
    /opt/theforeman/tfm/root/usr/share/gems/gems/clamp-1.1.2/lib/clamp/command.rb:63:in `run'
    /opt/theforeman/tfm/root/usr/share/gems/gems/hammer_cli-0.13.1/lib/hammer_cli/abstract.rb:29:in `run'
    /opt/theforeman/tfm/root/usr/share/gems/gems/clamp-1.1.2/lib/clamp/subcommand/execution.rb:11:in `execute'
    /opt/theforeman/tfm/root/usr/share/gems/gems/clamp-1.1.2/lib/clamp/command.rb:63:in `run'
    /opt/theforeman/tfm/root/usr/share/gems/gems/hammer_cli-0.13.1/lib/hammer_cli/abstract.rb:29:in `run'
    /opt/theforeman/tfm/root/usr/share/gems/gems/clamp-1.1.2/lib/clamp/command.rb:132:in `run'
    /opt/theforeman/tfm/root/usr/share/gems/gems/hammer_cli-0.13.1/bin/hammer:143:in `<top (required)>'
    /usr/bin/hammer:23:in `load'
    /usr/bin/hammer:23:in `<main>'

Can it be that the actual issue is trying to create another host, but with the same MAC and IPv4 address? 

Looking at the logs it seems that there is an issue validating the NIC, which too should not error and show a validation instead, but it would be good to verify first that this is the cause.

Mind trying to do the same, but change MAC as well as IP for the second host when trying to create in a different Org/Loc.

Sorry for the delay, I tested this on 6.4.1. 

This time using a different Mac-address and IP , I was still able to reproduce the issue.

In the logs I see this, 

2018-12-14T01:24:53 [I|app|] Started POST "/api/hosts" for 10.16.64.253 at 2018-12-14 01:24:53 -0500
2018-12-14T01:24:53 [I|app|b6d5e] Processing by Api::V2::HostsController#create as JSON
2018-12-14T01:24:53 [I|app|b6d5e]   Parameters: {"location_id"=>2, "organization_id"=>1, "host"=>{"name"=>"host1", "location_id"=>2, "organization_id"=>1, "environment_id"=>1, "ip"=>"148.172.224.44", "mac"=>"94:e3:d9:06:72:49", "architecture_id"=>1, "domain_id"=>1, "puppet_proxy_id"=>"1", "puppetclass_ids"=>[], "operatingsystem_id"=>3, "medium_id"=>1, "ptable_id"=>94, "compute_resource_id"=>4, "compute_attributes"=>{"volumes_attributes"=>{}}, "content_facet_attributes"=>{}, "subscription_facet_attributes"=>{}, "build"=>true, "managed"=>true, "enabled"=>true, "overwrite"=>true, "interfaces_attributes"=>[], "root_pass"=>"[FILTERED]"}, "apiv"=>"v2"}
2018-12-14T01:24:53 [I|app|b6d5e] Current user: foreman_admin (administrator)
2018-12-14T01:24:53 [I|app|b6d5e] Authorized user admin(Admin User)
2018-12-14T01:24:53 [I|app|b6d5e] Current user: admin (administrator)
2018-12-14T01:24:54 [W|app|b6d5e] Action failed
NoMethodError: undefined method `provided_attributes' for nil:NilClass
/usr/share/foreman/app/models/concerns/orchestration/compute.rb:30:in `compute_provides?'
/usr/share/foreman/app/models/nic/base.rb:173:in `compute_provides_ip?'
/usr/share/foreman/app/services/nic_ip_required/base.rb:58:in `compute_provides_ip?'
/usr/share/foreman/app/services/nic_ip_required/base.rb:20:in `required?'
/usr/share/foreman/app/models/nic/base.rb:157:in `require_ip4_validation?'
/usr/share/foreman/app/models/nic/base.rb:35:in `block in <class:Base>'

Satellite 6.4 is now End of Life. These bus will not be fixed on the 6.4 stream. Users of Satellite should upgrade to the latest version of Satellite to get access to the most current set of bugfixes and feature improvements.