The error occurs because UPS no longer supports the Shipping Manager software in QuickBooks, ACMN. We're currently in the process of switching providers, and I'll elaborate on the specifics below.

Establishing new connections to UPS accounts is unattainable since QuickBooks Desktop Enterprise no longer has a direct integration with UPS Shipping Manager. If you haven't set up shipping with your carrier, you won’t be able to do so until we launch our new Shipping Manager experience in May. With this, there will be a new notification in QuickBooks regarding this upcoming experience.

For more details about the new and improved shipping experience, refer to this article: Get ready for a new shipping experience in QuickBooks Desktop.

In the meantime, I suggest generating shipping labels directly through the UPS website. 

Additionally, consider organizing and managing your inventory, as this can assist with your shipping through this guide: Set up Advanced Inventory in QuickBooks Desktop. 

Furthermore, monitor your product costs to factor in shipping, customs duties, insurance, and miscellaneous items through this reference: Calculate landed costs in QuickBooks Desktop Enterprise.

If you need additional assistance with the shipping or inventory functionalities, add them in the comments below. Do you also need help with editing or updating items? Let us know, and we'll provide you with guidance.