Hi Xiong,
I see that you are getting an error when doing a punchout to APC from SAP ECC.
Please try the below given steps:
-Start Internet Explorer.
-On the Tools menu, click Internet Options.
-On the Security tab, click Trusted sites, and then click Sites.
-In the Add this Web site to the zone box, type the URL of the Web site that is affected, and then click Add.
-Click OK.
Now restart the browser and try again. If the error persists then please check with your local IT team. They should be able to help you. In case they are not able to resolve, then you will have to check with Ariba support by logging a ticket using connect.ariba.com. Ariba team will further try to diagnose it by enabling the logging on their side to see where exactly the issue is happening and help you further in resolving this.
Regards,
Nadeem Ahmed