Warning: Array to string conversion in ......validation.php

Hi Support
We have recently updated our testsite with Joomla! 3.10.11, Gantry 5.5.14, PHP 8 and Visforms 3.14.10 in this order.
We did problem-solve an error with forms displayed via a menu. Now all forms appear to be working fine. 

Our main problem is the warning message below. We have scoured Google and your forum without any luck. Also compared validation.php with an earlier version. It appears to have the same code on line 93. Until the Visforms update the previous version was working without any warning.. 

We would be grateful for your advice

Warning: Array to string conversion in /home1/auburnwo/public_html/woodturningonlinecom/templates/rt_interstellar/html/layouts/com_visforms/visforms/scripts/validation.php on line 93
 

Hello Kerry,

The validation.php file that generates the PHP warning is not an original Visforms file.

It is a custom override file in the template and is located below the template directory:
/home1/auburnwo/public_html/woodturningonlinecom/templates/rt_interstellar/html/layouts/

I'm assuming it's an outdated validation.php file.

Kind regards, Ingmar