Firefox added a new argument to the saveURI api (https://developer.mozilla.org/en-US/docs/Mozilla/Tech/XPCOM/Reference/Interface/nsIWebBrowserPersist) which broke our MyWebSteps. Version 1.3 has been updated to address this change.
In addition, from version 1.3, to save the users storage space, MyWebSteps will only save the thumbnail of part of a webpage rather than the whole webpage. This change would require only about 1.5GB rather than 5GB on the user’s hard disk each year.
Please download the new version at https://addons.mozilla.org/en-US/firefox/addon/mywebsteps/versions/?page=1#version-1.3