Encountering 'Uncaught (in promise) error' with redux-form Server-side Validation

This article was originally published on bmf-tech.com . Overview This post discusses an issue encountered when implementing server-side validation with redux-form. While manipulating promises and throwing redux-form's SubmissionError , an Uncaught (in promise) error occurred. Solution The issue was simply due to a missing return statement. Before Fix class Categories extends Component { onSubmit ( props ) { const { createCategory , fetchCategories , reset } = this . props ; createCategory ( props ). then (( res ) => { if ( res . error ) { console . log ( ' error ' ); throw new SubmissionError ({ name : ' User does not exist ' , _error : ' Login failed! ' }); } else { console . log ( ' success ' ); reset (); fetchCategories (); } }); } // Other parts omitted } After Fix class Categories extends Component { onSubmit ( props ) { const { createCategory , fetchCategories , reset } = this . props ; return createCategory ( props ). then (( res ) => { if ( res . error ) { console . log ( ' err