When attempting to add new user get following error message: "This page isn’t working www.acorkhill.com is currently unable to handle this request.
HTTP ERROR 500"
Otherwise Zenphoto seems to work properly. I am using the latest version. i have reinstalled the softeware but made no difference. PHP version according to web host is 7.2 but Zenphoto reports 5.6.40

Thanks for any help with this,
Anthony

Other errors in the logs (ZP or server)? How many users do you have? If you have a lot set the display to one per page on the options.

Thanks for your reply- there are nine users including myself - I want to add tenth user.

The debug log is:
{2496920:Mon, 16 Sep 2019 17:48:25 GMT} Zenphoto v1.5.4
USER ERROR: MySQLi Error: ( INSERT INTO [prefix]administrators (user, valid, id, pass, passupdate, passhash, rights, lastchangeuser, date) VALUES ('sally', '1', '-1', 'q/WNrXoYhGJWtAJOgY5CQaB2sx765W5hLJnC8O/RxCY=', '2019-09-16 18:48:25', '3', '6686561', 'acorkhill', '2019-09-16 18:48:25') ) failed. MySQLi returned the error Unknown column 'lastchangeuser' in 'field list' in /home/acorkhil/public_html/rpsec4/zp-core/functions-db-MySQLi.php on line 93
trigger_error called from query (functions-db-MySQLi.php [93])
from PersistentObject->save (class-persistentobject.php [352])
from Zenphoto_Administrator->save (lib-auth.php [1624])
from admin-users.php [231]

As far as I can tell the website is functioning normally otherwise.

Okay, that's another issue. If the column 'lastchangeuser' is really missing I don't know why. Please re-run setup, that should create it. If not let us know.

Did you update the way described on our site or using one of these install helpers some hosts offer?

Problem solved! Thank you for your help. I updated the site by your recommended method after deleting the zp-core folder. This corrected the problem.

Great, thanks for the feedback!