the title prop of a button must be a string - react native
I think you have closed the Button tag too early.
<Button
style={{fontSize: 20, color: 'green'}}
styleDisabled={{color: 'red'}}
onPress={() => this._handlePress()}> // <-- closed tag here
title="Press Me"
</Button>
Just close the tag after the title attribute
<Button
style={{fontSize: 20, color: 'green'}}
styleDisabled={{color: 'red'}}
onPress={() => this._handlePress()}
title="Press Me"
>
Press Me
</Button>
Button name should be written with title keyword
Example :
<Button
style={{fontSize: 20, color: 'green'}}
styleDisabled={{color: 'red'}}
onPress={() => this._handlePress()}
title="Press Me"
>
</Button>
title="Press Me" inside Button tag