I have tried to upgrade a SPFx project from Yeoman 1.3.4 to 1.4.0 as a result of this React is upgraded from version 14 to version 15.6.

As a result my code has gone from working to not working :-

private _showAlert(): void { const alert: React.ReactElement = React.createElement( Alert, { message: strings.CustomSearchPlaceholderModeOnAlert } ); ReactDom.render(alert, this.domElement); } 

Error :- [ts] Argument of type ‘typeof Alert’ is not assignable to parameter of type ‘string | ComponentClass | StatelessComponent’. Type ‘typeof Alert’ is not assignable to type ‘StatelessComponent’. Type ‘typeof Alert’ provides no match for the signature ‘(props: IAlertProps & { children?: ReactNode; }, context?: any): ReactElement’. import Alert

This is what came out of gulp serve :-

Error – typescript – src\webparts\reactSearchBox\ReactSearchBoxWebPart.ts(129,6): error TS2345: Argument of type ‘typeof Alert’ is not assignable to parameter of type ‘string | ComponentClass | StatelessComponent’.

IAlertProps :+

export interface IAlertProps {   /**    * Message to be rendered in h1.    */   message: string; } 

Alert :-

import * as React from 'react'; import { IAlertProps } from './IAlertProps';  declare const window: any;  /**  * Simple react component that shows h1 element with text.  */ export default class Alert extends React.Component<IAlertProps, void> {   public render(): React.ReactElement<IAlertProps> {     return (       <h1>{this.props.message}</h1>     );   } } 

Any Ideas anyone ?