React - setState() on unmounted component

Without seeing the render function is a bit tough. Although can already spot something you should do, every time you use an interval you got to clear it on unmount. So:

componentDidMount() {
    this.loadInterval = setInterval(this.loadSearches, this.props.pollInterval);
}

componentWillUnmount () {
    this.loadInterval && clearInterval(this.loadInterval);
    this.loadInterval = false;
}

Since those success and error callbacks might still get called after unmount, you can use the interval variable to check if it's mounted.

this.loadInterval && this.setState({
    loading: false
});

Hope this helps, provide the render function if this doesn't do the job.

Cheers

The question is why am I getting this error when the component should already be mounted (as its being called from componentDidMount) I thought it was safe to set state once the component is mounted ?

It is not called from componentDidMount. Your componentDidMount spawns a callback function that will be executed in the stack of the timer handler, not in the stack of componentDidMount. Apparently, by the time your callback (this.loadSearches) gets executed the component has unmounted.

So the accepted answer will protect you. If you are using some other asynchronous API that doesn't allow you to cancel asynchronous functions (already submitted to some handler) you could do the following:

if (this.isMounted())
     this.setState(...

This will get rid of the error message you report in all cases though it does feel like sweeping stuff under the rug, particularly if your API provides a cancel capability (as setInterval does with clearInterval).