Hi,
Overrule the error style of TextBox by placing this in one of your own native style files and change it to your requirements, take out elements you don't want to overrule: (I took this from the Core / widgets / textbox.js)
Edit: Don't forget to add imports for things like import and font, these come from custom-variables (.js)
export const TextBox = {
inputError: {
// autoCapitalize, placeholderTextColor, selectionColor, underlineColorAndroid and all TextStyle properties are allowed
color: input.errorColor,
borderColor: input.errorColor,
placeholderTextColor: input.errorColor,
underlineColorAndroid: input.underlineColorAndroid,
},
validationMessage: {
// All TextStyle properties are allowed
color: input.errorColor,
fontSize: font.size,
fontFamily: font.family,
},
};