SSL/TLS v. namespace.
Incident Report for TaxCloud
This afternoon learned that related to this TLS Cipher Upgrade our namespace declaration was changed from to

This namespace change was done with the best of intentions, but for implementations with cached WSDL data, this caused SOAP request errors. Our name space declaration has been reverted. Please reload our WSDL file ( if you are experiencing any issues.

We will not change our namespace ever again (even though it references http rather than https).
Posted Feb 14, 2016 - 21:59 PST