In case this helps anyone:
for those of you like me that suddenly got the “WARNING: An Error occurred, please refresh the page and try again.” using Zen Cart 1.5.1 – I dug around and for some reason when a new salemaker is being created its addin in 2 commas st the start of the field – which the MySQL cannot work with
so in
Open includes/modules/pages/specials/main_template_vars.php and find:
I changed
$sale_categories_all = substr($sale_categories_all, 1); // remove preceeding comma
too
$sale_categories_all = substr($sale_categories_all, 2); // remove preceeding 2 comma’s
and error went away – now I don’t know why this is happening now – as it was working fine
but for those that just want a solution try it - I don't guarantee that it won't have an effect further down the line :)
Thanks
Sarah