Another work story!
Yesterday we upgraded to Upgrade 17 + 18 of Cold Fusion 11, and ended up with a ton of errors that evening while scheduled tasks were running.
We have a service using CFHTTP which requests data from another local service with a complex query string. The step after this was failing, as the result from the CFHTTP request was very odd.
We did some production level troubleshooting, and found that the result was actually a Connection Failure.
We tested the same thing on Development, and the result was Connection Failure. Invalid Characters provided.
After that, we checked the url string, and discovered that there are spaces in the url. This was it. Spaces in a CFHTTP url parameter are no longer allowed.