Symptoms
On an attempt to place a new order for Azure CSP, checking the subdomain *.onmicrosoft.com works improperly: it periodically reports domains as free, despite those are in use.
Cause
Used version of the Azure CSP package uses external Yahoo! service to check the subdomain availability in Microsoft. Due to some connectivtity issue, the query run from Yahoo! to Microsoft returns a 400 Bad Request error, which is incorrectly treated by OA.
Resolution
It is recommended to upgrade Azure CSP to the version 4.5.2 or later. The latest version of the package uses new PC API which allows to check the subdomain directly in Microsoft.
In order to resolve the issue on older versions of Azure CSP, re-apply the script.js file according to the OA and application version per this article.