Form giving error on submit

My new chronoforms membership form is giving an error to some members that says: "The requested page cannot be found." The reference is Chronoform=efac-membership&gpage=page_2

My page 2 is empty so I'm not sure what the problem is but it's causing anxiety to our members. Can anyone suggest a solution?

Chris A

Here is a screen shot of the error message - reported by several different people using various platforms. https://www.efac.org.au/ScreenShot.png