I'm using Expresso Store 1.6.4 and EE 2.6.0. The inline errors are not working, the page just refreshes to the site homepage. If I remove the inline errors, the default EE error page displays correctly.
I'll just mention that we're also using Boldmindeds Publisher on this site as well, which has caused some issues on other parts of the site, so that could be an explanation.
Thanks,
{error:field_name}
tags for each field? Also, have you tried to disable Publisher to see if that makes a difference?