X-Cart forums - HERE is how to change invoice numbering with MYSQL

I asked my host to help me and here's what they wrote:

"The permissions of both perl and the file /var/www/vhosts/store.domain.com/httpdocs/patch.pl is setup correctly in the server. But when i logged in i was still getting the error."

P.S. My host gave me this "formula" to enter into "pearl path" field:

/usr/bin/perl

After I entered it, the patch/upgrade error disappeared. I hope this helps others as well. All I needed was these three words! /usr/bin/perl

I just entered that patch: ALTER TABLE xcart_orders AUTO_INCREMENT = xxxxxx; (where I replaced x'es with my desired number) and then I placed a test order and the order number is still "old".

UPDATE: I just found a partial solution: before I was trying to change a higher number (3000) to a lower number (2600) which for some logical reason did not work. Maybe because I already had test orders running at 3015...3016... etc. But now I patched the "sql" to the number "3500" and it worked. So the problem was that you can not go to a LOWER number, especially if a higher number order already exists. Perhaps I'll now try to delete ALL orders and see if I can get 2600 set up finally.

OK, now all is clear:

You can use:

ALTER TABLE xcart_orders AUTO_INCREMENT = xxxxxx;

only if you want to change lower order numeration into a bigger one.
And if you wish to change let's say 3015 into 2015 then you have to delete ALL the existing orders in your cart and only then you will be able to go below the existing numbers.