Title: Javascript error
Last modified: March 30, 2026

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# Javascript error

 *  Resolved [Spacetime](https://wordpress.org/support/users/spacetime/)
 * (@spacetime)
 * [2 months, 1 week ago](https://wordpress.org/support/topic/javascript-error-248/)
 * I see javascript errors in the console:
 * `Uncaught (in promise) {code: 'invalid_json', message: 'The response is not a
   valid JSON response.'{code: 'invalid_json', message: 'The response is not a valid
   JSON response.'}`
 * It seems the following script is causing issues:
 * `/wp-content/plugins/contact-form-7/includes/js/index.js?ver=6.1.5`
 * Please advise.
 * The page I need help with: _[[log in](https://login.wordpress.org/?redirect_to=https%3A%2F%2Fwordpress.org%2Fsupport%2Ftopic%2Fjavascript-error-248%2F%3Foutput_format%3Dmd&locale=en_US)
   to see the link]_

Viewing 4 replies - 1 through 4 (of 4 total)

 *  Plugin Author [Takayuki Miyoshi](https://wordpress.org/support/users/takayukister/)
 * (@takayukister)
 * [2 months, 1 week ago](https://wordpress.org/support/topic/javascript-error-248/#post-18867435)
 * What other plugins and theme do you use on the site?
 *  Thread Starter [Spacetime](https://wordpress.org/support/users/spacetime/)
 * (@spacetime)
 * [2 months, 1 week ago](https://wordpress.org/support/topic/javascript-error-248/#post-18867522)
 *     ```wp-block-code
       WordPress:               6.9.4Current Theme:           Readable Child 1.0.3  INSTALLED PLUGINS======================================* Ad Inserter Pro 2.8.12* Advanced Cron Manager 2.7.0* Advanced Custom Fields 6.7.2* Advanced Editor Tools 5.9.2* Classic Editor 1.6.7* Classic Widgets 0.3* Contact Form 7 6.1.5* DST Live Tracker 1.0.0* Easy WP SMTP 2.13.1* No Category Base (WPML) 1.4* Prismatic 3.7.4* Recent Posts Widget With Thumbnails 7.1.1* Related Posts By Taxonomy 2.7.8* Relevanssi 4.26.1* Simple Custom Post Order 2.6.0* W3 Total Cache 2.9.3* WP-Optimize - Clean, Compress, Cache 4.5.1* WP 2FA - Two-factor authentication for WordPress 3.1.1.2* Yoast SEO 27.2
       ```
   
 *  Plugin Author [Takayuki Miyoshi](https://wordpress.org/support/users/takayukister/)
 * (@takayukister)
 * [2 months, 1 week ago](https://wordpress.org/support/topic/javascript-error-248/#post-18867590)
 * Try switching to the default theme, deactivating all plugins excluding Contact
   Form 7, Classic Editor, Classic Widgets and Yoast SEO, and clearing all cache
   data.
 * [Why you are advised to deactivate plugins and switch to the default theme.](https://contactform7.com/2019/12/02/why-you-are-advised-to-deactivate-plugins-and-switch-to-the-default-theme/)
 *  Thread Starter [Spacetime](https://wordpress.org/support/users/spacetime/)
 * (@spacetime)
 * [2 months, 1 week ago](https://wordpress.org/support/topic/javascript-error-248/#post-18867677)
 * It was caused by W3 Total Cache plugin page caching.

Viewing 4 replies - 1 through 4 (of 4 total)

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to reply to this topic.

 * ![](https://ps.w.org/contact-form-7/assets/icon.svg?rev=2339255)
 * [Contact Form 7](https://wordpress.org/plugins/contact-form-7/)
 * [Frequently Asked Questions](https://wordpress.org/plugins/contact-form-7/#faq)
 * [Support Threads](https://wordpress.org/support/plugin/contact-form-7/)
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 * [Unresolved Topics](https://wordpress.org/support/plugin/contact-form-7/unresolved/)
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 * 4 replies
 * 2 participants
 * Last reply from: [Spacetime](https://wordpress.org/support/users/spacetime/)
 * Last activity: [2 months, 1 week ago](https://wordpress.org/support/topic/javascript-error-248/#post-18867677)
 * Status: resolved