Firstly, everybody helping out on this topic and the forum in general deserve shiny gold stars and karma for helping out free of charge. This really is a golden example of open source in action. I am composing a sonnet dedicated to Steve in particular for being such a hero. :thumbsup:
I had a very similar problem that kalcable was experiencing with the CVV2 contribution and one page checkout. I have been keeping my eye on this topic now for about six months and decided two days ago to try it again (forced to switch web hosts due to recent PCI DSS compliance issues and new SSL certificates). Here was my procedure:
I installed the vanilla osC v2.2 RC2a. Over this I installed the ready made store red bubble (highly recommended contrib). I imported my SQL for products, categories, etc. Then I configured the store and customised the design and text elements. I added my shipping modules and all payment modules except CVV2, which I saved until last because I knew it would run into problems working with OPC. Backing up at every step of the way until I was ready to give OPC a go...
...All of the horrible old errors I encountered with OPC last time were gone but I was still left with a bizarre problem. When I tried to select my credit card payment method on the checkout page (paypal standard and cheque method worked fine) I received the popup box error: "There was an error setting payment method, please inform "storename" about this error." After clicking OK I was not presented with any credit card input boxes, but was allowed to press continue at the bottom. This would reload the checkout page, saving all of the input I typed. But in the course of reloading, this time the credit card fields were visible and I could enter the credit card details BUT ONLY AFTER PRESSING THE SAME POPUP BOX ERROR MESSAGE 5 TIMES (presumably one for each of the credit card fields for cc_owner, cc_number, cc_cvv2, cc_expires_month, cc_expires_year ??? ).
Pressing continue this time reloaded the page once more, again saving all of my input, but the popup box error only appeared once. Pressing OK just once this time had all of the input saved. Pressing continue at the bottom successfully captured the details, saved them to the database and I was shown the checkout success page - as if nothing wrong had happened! So the functionality was working but only after going through error messages. Hmm...
...All I needed to do to fix was to copy the code posted by steve in post #1948. All fixed! Thank you so so much.
Evidence for working OPC with CVV2 store can be seen at www.naturalflow.co.uk/catalog.
I was not able to reproduce the other bugs mentioned earlier in this topic (touch wood). Now all that remains for me to solve are broken "buy now" buttons (that link to dead 404 error pages throughout the store) and on the checkout page next to my CVV2 field where it says "What is this?" (should link to a popup info box " <strong onclick="openexpwindow();">' . TEXT_EXPLANATION . '</strong>) " but these are more related to contribs other than OPC methinks.
If I can be of any use to anyone who needs to know specifics of how I configured OPC and my other installed contribs I'd be happy to help if I can. Perhaps I stumbled upon a compatible method by chance. Perhaps my patience and care editing files paid off. But I recon a lot of it is down to the red bubble ready made store. It contains a lot of the other useful contribs inside it, and getting OPC to work with it seems less hassle than other people's stories on this topic.
All that remains is for me to get SSL back up and running when my host gets around to mailing my CSR. Hopefully installing SSL won't upset OPC at all... I can't see how it would. Do I speak too soon? Tune in next time for another exciting episode of Adventures in OPC!!! :P
Many thanks once again! I will be donating when the cherry is on top of the cake and the fat lady is singing.