Most people that frequent this board do not use PHP I'm afraid.
However, in the end it's all the same and what really matters is the plaintext you're sending to the CCM.. so post that here and we can see if there's something to be figured out.
Also, activate debug level traces on the AXL Service (from the serviceability pages), and download those logs.. they will tell you quite a bit - often more than the error response.
And.. when do you get that error? when creating the request or when parsing the response? What ccm version do you have and do you create your requests by hand following the schema or using a code generator (the latter is unfortunately still flaky.. just today I found several issues in the very latest ccm release).
http://schemas.xmlsoap.org/soap/encoding/" xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/">SOAP-ENV:ClientContent is not allowed in prolog.http://www.cisco.com/AXL/1.0">5001Content is not allowed in prolog.
These are the paths to get to each CCX logs through CLI. They may be helpful if you are having issues accessing RTMT or downloading logs through it.
If you want to download them you have to prefix "file get " and you can add one of the options (re...