I experienced situation with Contact Form 7 on one WordPress website recently, when submit button didn’t want to work at all. Spinning circle didn’t appeared, not any message (error or succesfuly sent) email wasn’t sent, nothing. On click to Submit button just notning happened.
When I opened Developer Tools Console in Chrome browser, I got this error message:
JSON.parse: unexpected non-whitespace character after JSON data at line X column X of the JSON data
Some may see JSON.parse: unexpected character at line X column X of the JSON data
After hours of figuring out the solution, here is how I resolved it:
I found out that “WP Super Cache” plugin which was deleted previously, left two files that produced the error. The files
was in “wp-content” folder. I just deleted that two files and voila, Contact Form 7 submit button worked perfectly as it should.