3.9.0 upgrade array_merge error - undefined index error

[mikidudle]

Hi All,
I updated to VM 3.9.0 (from like 3.6.x x being the last update).  At the end of the update I saw a warning (see below) that concerns an array_merge() php command. I didn't see an issue but was concerned that there'd be a problem later.  After a few days we tried to add product to VM and when we check the front end for verification, we saw an 'Undefined index' error (shown below) at the top of the product page. We haven't seen this before.  Existing products do not exhibit this problem.  Any ideas?

Joomla!: 3.9.10
VM: 3.9.0
Browser: Firefox & IE
Win 7 - 64

/*WARNINGS AND ERRORS */
/*Warning received during upgrade*/
Warning: array_merge(): Argument #2 is not an array in [root...]/virtuemart/models/config.php line 548
Warning: array_unique() expects parameter 1 to be array, null given in [root...]/virtuemart/models/config.php line 549


/*Now, after adding a new product I get */
Undefined index: Itemid in [root...]/components/com_virtuemart/router.php on line 219

Thank you in advance for looking at this.
Miki

[StefanSTS]

Can you please specify your exact VirtueMart version like shown in VirtueMart control center on the left side below the VM menu and your PHP version.

There is no VM 3.9.0.

Regards
Stefan