SOAP API in SuiteCRM vs SugarCRM

Is there any documentation on the SOAP API changes since SugarCRM?

I’m attempting to migrate out of ACT! 2010 using a migration tool built for SugarCRM (Starfish ETL). The tech who’s working on it sent me this message…

I have been unable to resolve this. I am using the SOAP API as normal. I’ve refreshed the WSDL and continue to get this message even for the simplest of set_entry (Insert/Update) requests.

This is the message we are getting:

Client found response content type of ‘text/html; charset=UTF-8’, but expected ‘text/xml’. The request failed with an empty response.

Thanks in advance for your assistance.