Some IndieCommerce users have reported issues processing payments on Authorize.net. The message they are seeing is "This transaction cannot be accepted at this time due to system maintenance. Please try again later."
This corresponds to a known Authorize.net error message (code 901). We suspect this is due to an issue on Authorize.net's end but have not yet been able to confirm. Authorize.net's status page does not report anything related at this time; however, they are not always quick to update their status page. It can be seen here: https://status.authorize.net/
We are continuing to monitor this issue.