Error decoding JSON data. - Single Page Protect - SOLVED

[onlye]

Just added the Single Page Protect to a page and getting an error in browser
Error decoding JSON data.
The page has the .php extension. I have two table extensions on the page; Collapsible Table and MySQL CRUD. I also tried it on another page is same project, also with one table extension, Collapsible Table, with same error.
I cloned the page with the two tables and removed the tables and tried again. Same error.
Using the default protection method - PHP
Also looked at the files in the folder and I don't see a json file.
Thoughts?

[Pablo]

I don't think you can use Single Page protect in combination with other PHP code, because the page is only decrypted when it send to to the browser so the PHP interpreter cannot 'see' the code.
I suggest to use the standard login tools instead.