[horde] Fatal error during initial setup

[Mike]

I received this fatal error during initial setup of the "composer"  
version of horde.

A fatal error has occurred
strrpos(): Argument #1 ($haystack) must be of type string, array given
in /var/www/horde/vendor/horde/core/lib/Horde.php:221

1. Horde::verifySignedUrl() /var/www/horde/vendor/horde/horde/login.php:72
2. strrpos() /var/www/horde/vendor/horde/core/lib/Horde.php:221


This error occurs when I click on the "Mail" link in the browser window.

I'm wondering if I didn't configure something correctly using the directions.
It seems that Horde::verifySignedURL expects a string, but an array  
was sent instead.  I'm not sure why $vars->url would return an array  
or where it gets populated from.

I do have a database set up.
I authenticated using the IMAP server (it did this before I set that  
up as well).

Has anyone run into this before?

My search on the internet didn't produce anything helpful.

Mike B.