child theme not working after theme upgrade

Hi,

I just upgraded a theme and now my child theme is not showing up on the front end of the page ( it reads ‘failed to load’.)

I have switched to other themes so I’m sure that it’s the child theme.

How should I troubleshoot this. I.e. what should I look for first? and is there a way to prevent this from happening every time there is an upgrade?

This is my first wordpress site so I’m always troubleshooting in new territory.

Thanks,

Nicole