This post is about the Warning: Failed child context type: Invalid child context `virtualizedCell.cellKey` of type `number` supplied to `CellRenderer`, expected `string` If are working with the FlatList then you can see this warning.

If you check the code that you have written for the FlatList then you can see something similar to the below code.
<FlatList
keyExtractor={(item, index) => index}
data={this.state.serverData}
renderItem={({ item, index }) => (
<View style={styles.item}>
<Text style={styles.text}>
{item.id}
{'.'}
{item.title.toUpperCase()}
</Text>
</View>
)}
/>
If the above code is somewhat similar to you code then the problem is keyExtractor prop expects a string but you’re getting a number.
So to solve this issue you need to add toString while setting up the value for keyExtractor.
keyExtractor = { (item, index) => index.toString() };
This is how updated code will look like
<FlatList
keyExtractor={(item, index) => index.toString()}
data={this.state.serverData}
renderItem={({ item, index }) => (
<View style={styles.item}>
<Text style={styles.text}>
{item.id}
{'.'}
{item.title.toUpperCase()}
</Text>
</View>
)}
/>
This is how you can solve the warning: Failed child context type: Invalid child context virtualizedCell.cellKey of type number supplied to CellRenderer, expected string. If you still have any issue then you can also follow this thread.