Infinite loading & invalid_json error

Hi!
I have a problem on my website with Contact Form 7. After pressing ‘submit’ it causes infinite spinning wheel rotation and doesn’t show success message. However email is successfully sent.

I get error in console:

{code: "invalid_json", message: "The response is not a valid JSON response."}
code: "invalid_json"
message: "The response is not a valid JSON response."

Error is thrown in:
https://artbud.kyiv.ua/wp-content/plugins/contact-form-7/includes/js/index.js
On line: 312

Wordpress ver. 5.7.2

Installed and activated plugins:
Contact Form 7
Advanced Custom Fields 5.9.4
Photo Gallery 1.5.68
Redirection 5.1.1
Webcraftic Cyr to Lat reloaded 1.2.0
WP Google Maps 8.1.9

Steps I made to solve the issue:

• I tried to deactivate all plugins it didn’t help
• I tried to update permalinks in Settings->Permalinks
• I tried to create another contact form
• Everything works just fine on my demo webpage – https://artbud.neon-studio.site/

Reproduction steps:
1. Go to home page
2. Click on big yellow button with label ‘Обратный звонок’
3. Try to send message

I have the same problem with another form on this page – https://artbud.kyiv.ua/kontakty/
(When WP Google Maps activated it throws an error but if I deactivate this plugin I see error from Contact Form 7).

Thanks for your help in advance!

• This topic was modified 4 years, 8 months ago by atip. Reason: Added Wordpress version

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