Salesforce and SoapUI TLS 1.1 or higher

Salesforce is disabling TLS 1.0 and all new Sanboxes created after June 26, 2016 will require TLS 1.1 and above to communicate. More info here.

If you been using SoapUI on Windows to do some testing on the API, you will need to set the TLS version of it. To do this do the following:

1. Locate the 'vmoptions' file of SoapUI. This is normally located on the installation directory under the bin folder (e.g. C:\Program Files (x86)\SmartBear\Soap-5.3.0\bin\)
2. Open the file using your favorite editor
3. Add "-Dsoapui.https.protocols=SSLv3,TLSv1.1" at the end of the file ans save (without the double quotes)
4. Open SoapUI

Enjoy!

UPDATE: I found a complete guide that includes how to edit it for Linux and Mac here.