Title: React Error #321 for Custom Blocks
Last modified: October 25, 2021

---

# React Error #321 for Custom Blocks

 *  [sehqlr](https://wordpress.org/support/users/sehqlr/)
 * (@sehqlr)
 * [4 years, 6 months ago](https://wordpress.org/support/topic/react-error-321-for-custom-blocks/)
 * Hey y’all,
 * I’m a software engineer working for the Washington University in St. Louis library
   system. We have a WP site here (library.wustl.edu) and I’ve come across a problem
   for weeks now, and I am stuck. I am hoping that this forum will help me get closer
   to an answer.
 * Our current site was built by a third party, and they used external npm dependencies
   for their custom blocks in Gutenberg. The one that’s giving me trouble is `react-
   select`. The bug is that when you go to edit a block’s attributes in Gutenberg,
   something doesn’t load correctly and I get [Minified React error 321.](https://reactjs.org/docs/error-decoder.html?invariant=321)
   HOWEVER, it only happens when the Gutenberg plugin is activated. The current 
   workaround is to have the plugin disabled, but we need to make sure that this
   bug won’t come and hit us again in the future.
 * This is my first forum posting here, so I likely made a mistake or not provided
   enough information. I apologize for that.
    -  This topic was modified 4 years, 6 months ago by [Steven Stern (sterndata)](https://wordpress.org/support/users/sterndata/).

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

 *  Thread Starter [sehqlr](https://wordpress.org/support/users/sehqlr/)
 * (@sehqlr)
 * [4 years, 6 months ago](https://wordpress.org/support/topic/react-error-321-for-custom-blocks/#post-14993630)
 * I realized that I never included a code sample…
 *     ```
       render() {                                                               
               const multiple = this.props.isMulti;                             
               const handleChange = this.props.onChange;                        
               const { selected } = this.props;                                 
               console.log('PostTypePicker rendering now');                     
               console.log(this);                                               
               return (                                                         
                       <AsyncSelect                                             
                               isMulti={multiple}                               
                               value={this.rehydratePostTypeSelection(selected)}
                               loadOptions={this.loadOptions}                   
                               defaultOptions                                   
                               onChange={handleChange}                          
                       />                                                       
               );                                                               
       }
       ```
   
 * The console logs always print, and the `rehydratePostTypeSelection` function 
   also runs (because I have a few logging statements there too). But something 
   happens when this `AsyncSelect` component renders and triggers the exception.
    -  This reply was modified 4 years, 6 months ago by [sehqlr](https://wordpress.org/support/users/sehqlr/).
 *  Thread Starter [sehqlr](https://wordpress.org/support/users/sehqlr/)
 * (@sehqlr)
 * [4 years, 6 months ago](https://wordpress.org/support/topic/react-error-321-for-custom-blocks/#post-15030063)
 * For Your Information… I decided to [create an issue](https://github.com/JedWatson/react-select/issues/4893)
   in the react-select GitHub repository.
 *  [bornready](https://wordpress.org/support/users/bornready/)
 * (@bornready)
 * [4 years, 6 months ago](https://wordpress.org/support/topic/react-error-321-for-custom-blocks/#post-15030845)
 * Greetings,
 * I am a collaborator on the react-select project and was hoping to assist with
   this issue but it’s a bit unclear of how the Gutenberg plugin is working or even
   how to begin debugging.
 * The reported issue according to the console error seems to indicate that there
   are either multiple instances of react or a misuse of hooks, but we’re unable
   to replicate nor have we come across anything like this error before.
 * Please let me know if there is anything I can do on my end to assist in troubleshooting.
 *  [blauweb](https://wordpress.org/support/users/blauweb/)
 * (@blauweb)
 * [4 years, 4 months ago](https://wordpress.org/support/topic/react-error-321-for-custom-blocks/#post-15218010)
 * Hi,
 * I’m a webapp freelancer, and I’m currently expanding my skills with WP Gutenbergs
   custom blocks.
 * I run into the same error while developing my first custom block, and in my case
   the origin of the error was in the save() function of the custom block .js file.
   
   It was due to the fact, that my RichText element was wrongly rendering. Whereas
   in the edit() function you just use “<RichText />”, in the save() function I 
   had to refer to <RichText.Content />, which resembles my attributes structure-
   > attributes:{content: {…}}.
 * I hope this will help you solve your issue.
    -  This reply was modified 4 years, 4 months ago by [blauweb](https://wordpress.org/support/users/blauweb/).
      Reason: typo

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

The topic ‘React Error #321 for Custom Blocks’ is closed to new replies.

 * In: [Developing with WordPress](https://wordpress.org/support/forum/wp-advanced/)
 * 4 replies
 * 3 participants
 * Last reply from: [blauweb](https://wordpress.org/support/users/blauweb/)
 * Last activity: [4 years, 4 months ago](https://wordpress.org/support/topic/react-error-321-for-custom-blocks/#post-15218010)
 * Status: not resolved

## Topics

### Topics with no replies

### Non-support topics

### Resolved topics

### Unresolved topics

### All topics