Cannot add category

When I try to create a category in Lightspeed retail i get the error 'Could not add Category'
When I try via the API I get a 500 server error.
[httpCode] => 500
[httpMessage] => Internal Server Error
[message] => An error has occurred and we've been notified. Please try again and if this problem continues please contact support.
[errorClass] => InternalServerErrorHttpException