Whoops! Sorry, but you are not allowed

Upgraded one site from 139g to 139h
Several customers are getting this message once they are logged in and trying to checkout

"Whoops! Sorry, but you are not allowed to perform the action requested.
You are still logged in to your account and may continue shopping. Please
choose a destination from a menu."

Appears to be customers who visited just before and after the upgrade.
I have cleared the sessions table and told them to clear their cache.
I had the problem myself with one test account and I still cannot get it to work. While using another test account the checkout worked fine.

Using php 5.2.14

I have upgraded several other sites with no problems
Have I missed something in this upgrade?
Any suggestions?

I have exactly this same problem. Upgraded from 1.3.9a to 1.3.9h, also moved the cart to the root directory at the same time.
Server Information
Database: MySQL 5.0.27
HTTP Server: Apache/2.2.3 (Fedora)
PHP Version: 5.1.6 (Zend: 2.1.0) PHP Memory Limit: 16M
Zen Cart 1.3.9h
Database Patch Level: 1.3.9a
v1.3.9a [2010-04-24 10:25:25] (Version Update 1.3.8->1.3.9a)
v1.3.8 [2009-07-23 11:20:26] (Fresh Installation)

I have contacted the web host about the old php version, they have agreed to upgrade it to 5.2.13, soon. In the meantime I changed the files as mentioned elsewhere, as the product details weren't visible.

Have ih2, ceon uri, ceon manual card, and a few other mods. It's been a big effort to get them all playing nicely with each other and the new upgrade.

I've checked all my files using winmerge and can't find anything else that may cause a problem.
My site www.fairh a v e n.co.nz

Run out of ideas, please help.

Added note: Web host have upgraded php, no change has resulted.
Error log says: [08-Nov-2010 15:27:27] PHP Fatal error: Call to undefined function set_inc_ex_display() in /var/www/html/includes/templates/fairhaven/templates/tpl_shopping_cart_default.php on line 139
Also, I had tried to install module include_and_exclude_tax_in_prices_nettgross_1-23a but it didn't work so I uninstalled it.

heatherm:

Added note: Web host have upgraded php, no change has resulted.
Error log says: [08-Nov-2010 15:27:27] PHP Fatal error: Call to undefined function set_inc_ex_display() in /var/www/html/includes/templates/fairhaven/templates/tpl_shopping_cart_default.php on line 139
Also, I had tried to install module include_and_exclude_tax_in_prices_nettgross_1-23a but it didn't work so I uninstalled it.
It would seem that you've not completely uninstalled it, else you wouldn't be getting those errors.

Hi :)
There was an install.sql, but not an uninstall.sql, so I'm not sure if I did that bit right.

The function calls are in PHP files, not SQL.

But, that's all a discussion for another thread, and unrelated to the topic of this thread.

gilby:

Upgraded one site from 139g to 139h
Several customers are getting this message once they are logged in and trying to checkout

"Whoops! Sorry, but you are not allowed to perform the action requested.
You are still logged in to your account and may continue shopping. Please
choose a destination from a menu."

I have upgraded several other sites with no problems
Have I missed something in this upgrade?
Any suggestions?

Yes I had indeed missed something!!!
An addon I was using on this site had a pre 139g version of
\includes\classes\shopping_cart.php in it that had not been updated.
All working now!

Easy to miss, when the error message is slightly misleading! Turned out to be the 'site wide, category & product mark up' module, doesn't work with 1.3.9h. Thanks anyway, DrByte.