PANDB Cloud Agent Server certificate validation failed due to "self signed certificate in certificate chain"

• Proxy Server/SSL decryption Server used between Firewalls and Palo Alto URL Cloud.
• System logs (show log system) reports certificate errors

PANDB Cloud Agent Server certificate validation failed. Dest Addr: s0000.urlcloud.paloaltonetworks.com, Reason: self signed certificate in certificate chain

• Devsrv,log (less mp-log devsrv.log) reports the following messages

Perform download from cloud with result Peer certificate cannot be authenticated with given CA certificates.
Error:  pan_cloud_agent_download_cloud_list(pan_cloud_agent_connect.c:1747): PAN-DB cloud list loading failed (ERROR:Peer certificate cannot be authenticated with given CA certificates).
Error:  pan_cloud_agent_get_curl_connection(pan_cloud_agent_connect.c:2544): URL cloud list is empty. Cannot initiate cloud connection.
Warning:  pan_cloud_agent_get_curl_connection(pan_cloud_agent_connect.c:2711): cannot elect a cloud
Failed to open connection with the cloud after 117250 consecutive tries.
path : https://s0000.urlcloud.paloaltonetworks.com/urlcloud_list, path
Downloading URL database via proxy server: XXX.XXX.XXX.XXX:8080
A connection with proxy server is established
Error:  verify_cb(pan_ssl_curl_utils.c:615): Error with certificate at depth: 1
Error:  verify_cb(pan_ssl_curl_utils.c:617): Basic Validation of x509 cert Fail ; Code :  19 
Error:  verify_cb(pan_ssl_curl_utils.c:620): Issuer = /C=XX/ST=XXX/L=XXX/O=XXX/OU=XXX/CN=XYZ
Error:  verify_cb(pan_ssl_curl_utils.c:623): Subject = /C=XX/ST=XXX/L=XXX/O=XXX/OU=XXX/CN=XYZ
Error:  verify_cb(pan_ssl_curl_utils.c:626): Failed to validate x509 cert from ctx: (19) self signed certificate in certificate chain

• The proxy server information like XXX.XXX.XXX:8080 is different in every environment.
• And Issuer and Subject are also different in every environment.

• Palo Alto Firewalls
• Supported PAN-OS
• Appliance with SSL Decryption

1. Whitelist the Palo Alto Networks Cloud servers to exclude them from SSL Decryption.
2. The connection should now be successful.