Where and what is mygrid.properties

mygrid.properties is a configuration file for Taverna that includes the HTTP proxy configuration and a list of services that is to be populated in the Available services panel.

To locate mygrid.properties on a Mac, Ctrl-Click on the Taverna application, select Show package content, switch to Column view, and navigate down through Contents / Resources / Java / conf. Right click on mygrid.properties to Open with... -> Other and select your favourite text editor, say TextEdit.

In Windows and Linux the conf folder is found together with the runme.bat and runme.sh of your unpacked installation folder.