React is not defined

[pnahuy2]

Got this error in DNN 8.x:
Uncaught ReferenceError: React is not defined
at Object.7 (Map.js?cdv=55:1)
at n (Map.js?cdv=55:1)
at Map.js?cdv=55:1
at Object.9../icons.jsx (Map.js?cdv=55:1)
at n (Map.js?cdv=55:1)
at Map.js?cdv=55:1
at Object.2../forms/checkbox.jsx (Map.js?cdv=55:1)
at n (Map.js?cdv=55:1)
at Map.js?cdv=55:1
at Object.1../ConnectMapSettings.jsx (Map.js?cdv=55:1)