React createElement type is invalid -- expected a string

Question

Trying to get react-router  v4 0 0  and react-hot-loader  3 0 0-beta 6  to play nicely  but getting the following error in the browser console  Warning  React createElement  type is invalid -- expected a string  for built-in components  or a class function  for composite components  but got  undefined  You likely forgot to export your component from the file it s defined in   index js  import React from  react   import ReactDom from  react-dom   import routes from    routes js   require  jquery    import  bootstrap dist css bootstrap min css   import  bootstrap dist js bootstrap min js   import    css main css    const renderApp    appRoutes    gt        ReactDom render appRoutes  document getElementById  root         renderApp  routes       routes js  import React from  react   import   AppContainer   from  react-hot-loader   import   Router  Route  browserHistory  IndexRoute   from  react-router   import store from    store store js   import   Provider   from  react-redux   import App from    containers App jsx   import Products from    containers shop Products jsx   import Basket from    containers shop Basket jsx    const routes        gt          lt AppContainer gt           lt Provider store  store  gt               lt Router history  browserHistory  gt                   lt Route path  quot   quot  component  App  gt                       lt IndexRoute component  Products    gt                       lt Route path  quot  basket quot  component  Basket    gt                   lt  Route gt               lt  Router gt           lt  Provider gt       lt  AppContainer gt       export default routes

User · Answer

xxxxx prototype       dxxxx  PropTypes object isRequired     eslint-disable-line react forbid-prop-types     You must add    eslint-disable-line react forbid-prop-types  then it work

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I just spent 30 minutes trying to solve this BASIC basic issue   My problem was I was importing react native elements  eg import React    Text  Image  Component   from  react    And trying to use them  which caused me to receive this error   Once I switch from  lt Text gt  to  lt p gt  and  lt Image gt  to  lt img gt  everything worked as expected

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EDIT  You are complexifying the process  Just do this    index js   import React from  react   import ReactDom from  react-dom   import routes from    routes js   require  jquery    import  bootstrap dist css bootstrap min css   import  bootstrap dist js bootstrap min js   import    css main css    ReactDom render  lt routes   gt   document getElementById  root       routes js   import React from  react   import   AppContainer   from  react-hot-loader   import   Router  Route  browserHistory  IndexRoute   from  react-router   import store from    store store js   import   Provider   from  react-redux   import App from    containers App jsx   import Products from    containers shop Products jsx   import Basket from    containers shop Basket jsx    const routes        lt AppContainer gt           lt Provider store  store  gt               lt Router history  browserHistory  gt                   lt Route path     component  App  gt                       lt IndexRoute component  Products    gt                       lt Route path   basket  component  Basket    gt                   lt  Route gt               lt  Router gt           lt  Provider gt       lt  AppContainer gt    export default routes

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In my case I just had to upgrade from react-router-redux to react-router-redux next  I m assuming it must have been some sort of compatibility issue

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I was getting this error and none of the responses was my case  it might help someone googling   I was defining a Proptype wrong   ids  PropTypes array PropTypes string    It should be   ids  PropTypes arrayOf PropTypes string    VSCode and the compile error didnt give me a correct hint

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I was getting this error as well   I was using   import BrowserRouter from  react-router-dom    Fix was doing this  instead   import   BrowserRouter   from  react-router-dom

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What missing for me was I was using   import   Router  Route  browserHistory  IndexRoute   from  react-router     instead or correct answer should be    import   BrowserRouter as Router  Route   from  react-router-dom     Ofcourse you need to add npm package react-router-dom   npm install react-router-dom next --save

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For future googlers   My solution to this problem was to upgrade react and react-dom to their latest versions on NPM  Apparently I was importing a Component that was using the new fragment syntax and it was broken in my older version of React

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flow  import React from  react   import   styleLocal   from    styles   import     View    Text    TextInput    Image    from  react-native   import   TouchableOpacity   from  react-native-gesture-handler    export default React forwardRef  props  ref    gt    const   onSeachClick  onChangeTextSearch      otherProps     props     return            lt View style  styleLocal sectionStyle  gt           lt TouchableOpacity onPress  onSeachClick  gt               lt Image                                                   source  require        assets imgs search png                        style  styleLocal imageStyle    gt                   lt  TouchableOpacity gt               lt TextInput                 style    flex  1  fontSize  18                    placeholder  quot Search Here quot                  underlineColorAndroid  quot transparent quot                  onChangeText   text    gt    onChangeTextSearch text                   gt           lt  View gt            import IGPSSearch from        components IGPSSearch    lt Search onSeachClick  onSeachClick  onChangeTextSearch   onChangeTextSearch  gt   lt  Search gt

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React Fragment   fixed the issue for me  Error Code    return                lt section className  classes itemForm  gt                lt Card gt                lt  Card gt                lt  section gt             Fix   return          lt React Fragment gt           lt section className  classes itemForm  gt            lt Card gt            lt  Card gt            lt  section gt         lt  React Fragment gt

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In my case  the error occurred when trying to use ContextApi  I have mistakenly used   const MyContext        gt  createContext     But it should have been defined as   const MyContext   createContext     I am posting it here so that future visitors who get stuck on such a silly mistake will get it helpful to avoid hours of headache  coz this is not caused by incorrect import export

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Circular dependency is also one of the reasons for this   in general

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It s quite simple  really  I got this issue when I started coding React  and the problem is almost always because the import   import React    memo   from  react     You can use destructuring this because react lib has a property as memo  but you can not destructuring something like this  import   user   from  assets images icons Profile svg     because it s not a object   Hope it helps

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I had this problem when I added a css file to the same folder as the component file   My import statement was   import MyComponent from     MyComponent    which was fine when there was only a single file  MyComponent jsx   I saw this format in an example and gave it a try  then forgot I d done it   When I added MyComponent scss to the same folder  the import then failed  Maybe JavaScript loaded the  scss file instead  and so there was no error   My conclusion  always specify the file extension even if there is only one file  in case you add another one later

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Most of the time this indicates an import export error  But be careful to not only make sure the referenced file in the stack trace is well exported itself  but also that this file is importing other components correctly  In my case the error was like this    x000D   x000D  import React from  react   x000D   x000D     Note the  css at the end  this is the cause of the error  x000D  import SeeminglyUnimportantComponent from    SeeminglyUnimportantComponent css   x000D   x000D  const component    props    gt                x000D     lt div gt  x000D       lt SeeminglyUnimportantComponent   gt  x000D              component code here     x000D     lt  div gt      x000D     x000D   x000D  export default component  x000D   x000D   x000D

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This is not necessary a direct issue related to import export  In my case  I was rendering a child element inside a parent element and the child element has jsx element   tag which is used but not imported  I imported it and I used it then it fixed the issue  So the problem was in jsx elements which are inside the child element NOT the export of child element itself

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Try this  npm i react-router-dom next   in your App js  import   BrowserRouter as Router  Route   from  react-router-dom   const Home        gt   lt h1 gt Home lt  h1 gt   const App        gt      lt Router gt       lt Route path     component  Home    gt     lt  Router gt     export default App

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In my case I forgot to import and export my  new  elements called by the render in the index js file

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I was getting this error as well  I was using  import ReactDOM from  react-dom   Fix was doing this  instead  import  ReactDOM  from  react-dom

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In simply words  somehow the following is happening   render         return            lt MyComponent   gt     MyComponent is undefined             It may not necessarily be related with some incorrect import or export   render            MyComponent may be undefined here  for example      const MyComponent   this wizards this currentStep        return            lt MyComponent   gt

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This issue has occurred to me when I had a bad reference in my render return statement   point to a non existing class   Also check your return statement code for bad references

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In my case  the order in which you create the component and render  mattered  I was rendering the component before creating it  The best way is to create the child component and then the parent components and then render the parent component  Changing the order fixed the issue for me

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The application that I was working on  stored the name of react components as a widget configuration in the browser storage  Some of these components got deleted and the app was still trying to render them  By clearing the browser cache  I was able to resolve my issue

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Most of the time this is due to an incorrect export import   Common error      File  LeComponent js export class LeComponent extends React Component             File  App js import LeComponent from    LeComponent     Possible option      File  LeComponent js  export default class LeComponent extends React Component             File  App js import LeComponent from    LeComponent     There are a few ways it could be wrong  but that error is because of an import export mismatch 60  of the time  everytime    Edit  Typically you should get a stacktrace that indicates an approximate location of where the failure occurs  This generally follows straight after the message you have in your original question    If it doesn t show  it might be worth investigating why  it might be a build setting that you re missing   Regardless  if it doesn t show  the only course of action is narrowing down where the export import is failing    Sadly  the only way to do it  without a stacktrace is to manually remove each module submodule until you don t get the error anymore  then work your way back up the stack    Edit 2  Via comments  it was indeed an import issue  specifically importing a module that didn t exist

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If you have this error when testing a component  make sure that every child component render correctly when run alone  if one of your child component depend on external resources to render  try to mock it with jest or any other mocking lib   Exemple   jest mock  pathToChildComponent        gt   mock-child-component

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Array of components  A common way to get this error is using an array of components  with a positional index used to select the component to render from the array  I saw a code like this many times   const checkoutSteps    Address  Shipment  Payment   export const Checkout     step     gt       const ToRender   checkoutSteps step     return        lt ToRender   gt          This is not necessary bad code  but if you call it with a wrong index  eg -1  or 3 in this case   the ToRender component will be undefined  throwing the React createElement  type is invalid    error    lt Checkout step  0    gt      lt Address   gt   lt Checkout step  1    gt      lt Shipment   gt   lt Checkout step  2    gt      lt Payment   gt   lt Checkout step  3    gt     undefined  lt Checkout step  -1    gt     undefined   A rational solution  You should protect yourself and your collegues from this hard-to-debug code using a more explicit approach  avoiding magic numbers and using PropTypes   const checkoutSteps       address  Address    shipment Shipment    payment  Payment    const propTypes       step  PropTypes oneOf   address    shipment    payment           TIP  easier to maintain const propTypes       step  PropTypes oneOf Object keys checkoutSteps          const Checkout     step     gt       const ToRender   checkoutSteps step     return        lt ToRender   gt         Checkout propTypes   propTypes  export default Checkout   And your code will look like this      OK  lt Checkout step  address    gt      lt Address   gt   lt Checkout step  shipment    gt      lt Shipment   gt   lt Checkout step  payment    gt      lt Payment   gt      Errors  lt Checkout step  wrongstep    gt     explicit error  step must be one of      lt Checkout step  3    gt     explicit error  same as above   lt Checkout step  myWrongVar    gt     explicit error  same as above    Benefits of this approach   code is more explicit  you can clearly see what you want to render you don t need to remember the numbers and their hidden meaning  1 is for Address  2 is for     errors are explicit too no headache for your peers

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It means your import export is incorrect   Check newly added import exports  In my case I was using curly brackets unnecessary  Issue got resolved automatically when I removed these curly brackets   import   OverlayTrigger   from  react-bootstrap OverlayTrigger

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This is an error that is some how had to debug  As it has been said many times  improper import export can cause this error but surprisingly i got this error from a small bug in my react-router-dom authentication setup below is my case   WRONG SETUP   const PrivateRoute      component  Component     rest      gt         lt Route             rest          render   props    gt   token    lt Component     props    gt     lt Redirect to    pathname    login       gt          gt       CORRECT SETUP   const PrivateRoute      component  Component  token     rest      gt         lt Route             rest          render   props    gt   token    lt Component     props    gt     lt Redirect to    pathname    login       gt          gt       The only difference was I was deconstructing the token in the PrivateRoute component  By the way the token is gotten from localstorage like this const token   localStorage getItem  authUser    so if it is not there I know the user is not authenticated  This can also cause that error

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I was missing a React Fragment    function Bar   children         return        lt div gt        children       lt  div gt          function Foo       return        lt Bar gt         lt Baz  gt         lt Qux  gt       lt  Bar gt           The code above throws the error above  But this fixes it    lt Bar gt     lt  gt       lt Baz  gt       lt Qux  gt     lt   gt   lt  Bar gt

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In my case  I have added the same custom component as a prop instead of actual prob    import AddAddress from        components Manager AddAddress            class Add extends React PureComponent         render             const             history            addressFormData            formErrors            addressChange            addAddress            isDefault            defaultChange             this props        Error      return            lt AddAddress           addressFormData  addressFormData            formErrors  formErrors            addressChange  addressChange            addAddress  AddAddress     here i have used the Component name as probs in same component itself instead of prob           isDefault  isDefault            defaultChange  defaultChange            gt         lt  SubPage gt   Solution  return        lt AddAddress       addressFormData  addressFormData        formErrors  formErrors        addressChange  addressChange        addAddress  addAddress     removed the component name and give prob name       isDefault  isDefault        defaultChange  defaultChange        gt     lt  SubPage gt

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I think the most important thing to realize when troubleshooting this bug is that it manifests when you attempt to instantiate a component that doesn t exist   This component doesn t have to be imported   In my case I was passing components as properties   I forgot to update one of the calls to properly pass the component after some refactoring   Unfortunately  since JS isn t statically typed my bug wasn t caught  and it took some time to figure out what was happening     To troubleshoot this bug inspect the component before you render it  to make sure that it s the type of component you expect

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I got the exactly same error  Do this instead  npm install react-router next  react-router-dom next npm install --save history

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You need to be aware of named export and default export  See When should I use curly braces for ES6 import   In my case  I fixed it by changing from  import Provider from  react-redux    to  import   Provider   from  react-redux

[reactjs] React.createElement: type is invalid -- expected a string

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