Cannot update a component while rendering a different component warning

I am getting this warning in react:

index.js:1 Warning: Cannot update a component (`ConnectFunction`) 
while rendering a different component (`Register`). To locate the 
bad setState() call inside `Register` 

I went to the locations indicated in the stack trace and removed all setstates but the warning still persists. Is it possible this could occur from redux dispatch?

my code:

register.js

class Register extends Component {
  render() {
    if( this.props.registerStatus === SUCCESS) { 
      // Reset register status to allow return to register page
      this.props.dispatch( resetRegisterStatus())  # THIS IS THE LINE THAT CAUSES THE ERROR ACCORDING TO THE STACK TRACE
      return <Redirect push to = {HOME}/>
    }
    return (
      <div style = {{paddingTop: "180px", background: 'radial-gradient(circle, rgba(106,103,103,1) 0%, rgba(36,36,36,1) 100%)', height: "100vh"}}>
        <RegistrationForm/>
      </div>
    );
  }
}

function mapStateToProps( state ) {
  return {
    registerStatus: state.userReducer.registerStatus
  }
}

export default connect ( mapStateToProps ) ( Register );

function which triggers the warning in my registerForm component called by register.js

handleSubmit = async () => {
    if( this.isValidForm() ) { 
      const details = {
        "username": this.state.username,
        "password": this.state.password,
        "email": this.state.email,
        "clearance": this.state.clearance
      }
      await this.props.dispatch( register(details) )
      if( this.props.registerStatus !== SUCCESS && this.mounted ) {
        this.setState( {errorMsg: this.props.registerError})
        this.handleShowError()
      }
    }
    else {
      if( this.mounted ) {
        this.setState( {errorMsg: "Error - registration credentials are invalid!"} )
        this.handleShowError()
      }
    }
  }

Stacktrace:

This warning was introduced since React V16.3.0.

If you are using functional components you could wrap the setState call into useEffect.

Code that does not work:

const HomePage = (props) => {
    
  props.setAuthenticated(true);

  const handleChange = (e) => {
    props.setSearchTerm(e.target.value.toLowerCase());
  };

  return (
    <div key={props.restInfo.storeId} className="container-fluid">
      <ProductList searchResults={props.searchResults} />
    </div>
  );
};

Now you can change it to:

const HomePage = (props) => {
  // trigger on component mount
  useEffect(() => {
    props.setAuthenticated(true);
  }, []);

  const handleChange = (e) => {
    props.setSearchTerm(e.target.value.toLowerCase());
  };

  return (
    <div key={props.restInfo.storeId} className="container-fluid">
      <ProductList searchResults={props.searchResults} />
    </div>
  );
};

Just coming here because I just had this issue and it took me a bit of digging around before I realised what I'd done wrong - I just wasn't paying attention to how I was writing my functional component.

Figured I'd leave an answer here in case anyone comes looking, and they made the same simple mistake that I did.

I was doing this:

const LiveMatches = (props: LiveMatchesProps) => {
  const {
    dateMatches,
    draftingConfig,
    sportId,
    getDateMatches,
  } = props;

  if (!dateMatches) {
    const date = new Date();
    getDateMatches({ sportId, date });
  };

  return (<div>{component stuff here..}</div>);
};

I had just forgotten to use useEffect before dispatching my redux call of getDateMatches()

So stupid and something I had been doing in every other component, haha.

So it should have been:

const LiveMatches = (props: LiveMatchesProps) => {
  const {
    dateMatches,
    draftingConfig,
    sportId,
    getDateMatches,
  } = props;

  useEffect(() => {
    if (!dateMatches) {
      const date = new Date();
      getDateMatches({ sportId, date });
    }
  }, [dateMatches, getDateMatches, sportId]);

  return (<div>{component stuff here..}</div>);
};

Simple and silly mistake, but took a while to realise it, so hopefully this helps out someone else with this issue.

I fixed this issue by removing the dispatch from the register components render method to the componentwillunmount method. This is because I wanted this logic to occur right before redirecting to the login page. In general it's best practice to put all your logic outside the render method so my code was just poorly written before. Hope this helps anyone else in future :)

My refactored register component:

class Register extends Component {

  componentWillUnmount() {
    // Reset register status to allow return to register page
    if ( this.props.registerStatus !== "" ) this.props.dispatch( resetRegisterStatus() )
  }

  render() {
    if( this.props.registerStatus === SUCCESS ) { 
      return <Redirect push to = {LOGIN}/>
    }
    return (
      <div style = {{paddingTop: "180px", background: 'radial-gradient(circle, rgba(106,103,103,1) 0%, rgba(36,36,36,1) 100%)', height: "100vh"}}>
        <RegistrationForm/>
      </div>
    );
  }
}

If useEffect cannot be used in your case or if the error is NOT because of Redux

I used setTimeout to redirect one of the two useState variables to the callback queue.

I have one parent and one child component with useState variable in each of them. The solution is to wrap useState variable using setTimeout:

setTimeout(() => SetFilterData(data), 0);

Example below

Parent Component

import ExpenseFilter from '../ExpensesFilter'
    
function ExpensesView(props) {
    
    const [filterData, SetFilterData] = useState('')
    
    const GetFilterData = (data) => {
       // SetFilterData(data);

       //*****WRAP useState VARIABLE INSIDE setTimeout WITH 0 TIME AS BELOW.*****
       setTimeout(() => SetFilterData(data), 0);
    
    }
    
    const filteredArray = props.expense.filter(expenseFiltered => 
      expenseFiltered.dateSpent.getFullYear().toString() === filterData);
    
    
    return (
    <Window>
      <div>
        <ExpenseFilter FilterYear = {GetFilterData}></ExpenseFilter>

Child Component

const ExpensesFilter = (props) => {
    
    const [filterYear, SetFilterYear] = useState('2022')
    
    const FilterYearListener = (event) => {
        event.preventDefault()
        SetFilterYear(event.target.value)
    }
    
    props.FilterYear(filterYear)
    
    return (

TL;DR; For my case, what I did to fix the warning was to change from useState to useRef

react_devtools_backend.js:2574 Warning: Cannot update a component (`Index`) while rendering a different component (`Router.Consumer`). To locate the bad setState() call inside `Router.Consumer`, follow the stack trace as described in https://reactjs.org/link/setstate-in-render
    at Route (http://localhost:3000/main.bundle.js:126692:29)
    at Index (http://localhost:3000/main.bundle.js:144246:25)
    at Switch (http://localhost:3000/main.bundle.js:126894:29)
    at Suspense
    at App
    at AuthProvider (http://localhost:3000/main.bundle.js:144525:23)
    at ErrorBoundary (http://localhost:3000/main.bundle.js:21030:87)
    at Router (http://localhost:3000/main.bundle.js:126327:30)
    at BrowserRouter (http://localhost:3000/main.bundle.js:125948:35)
    at QueryClientProvider (http://localhost:3000/main.bundle.js:124450:21)

The full code for the context of what I did (changed from the lines with // OLD: to the line above them). However this doesn't matter, just try changing from useState to useRef!!

import { HOME_PATH, LOGIN_PATH } from '@/constants';
import { NotFoundComponent } from '@/routes';
import React from 'react';
import { Redirect, Route, RouteProps } from 'react-router-dom';
import { useAccess } from '@/access';
import { useAuthContext } from '@/contexts/AuthContext';
import { AccessLevel } from '@/models';

type Props = RouteProps & {
  component: Exclude<RouteProps['component'], undefined>;
  requireAccess: AccessLevel | undefined;
};

export const Index: React.FC<Props> = (props) => {
  const { component: Component, requireAccess, ...rest } = props;

  const { isLoading, isAuth } = useAuthContext();
  const access = useAccess();
  const mounted = React.useRef(false);
  // OLD: const [mounted, setMounted] = React.useState(false);

  return (
    <Route
      {...rest}
      render={(props) => {
        // If in indentifying authentication state as the page initially loads, render a blank page
        if (!mounted.current && isLoading) return null;
        // OLD: if (!mounted && isLoading) return null;

        // 1. Check Authentication is one step
        if (!isAuth && window.location.pathname !== LOGIN_PATH)
          return <Redirect to={LOGIN_PATH} />;
        if (isAuth && window.location.pathname === LOGIN_PATH)
          return <Redirect to={HOME_PATH} />;

        // 2. Authorization is another
        if (requireAccess && !access[requireAccess])
          return <NotFoundComponent />;

        mounted.current = true;
        // OLD: setMounted(true);
        return <Component {...props} />;
      }}
    />
  );
};

export default Index;