I keep getting an alphanumeric character error when sending a transaction.

This is a known bug that we're currently working on a fix for. At present, if a non-alphanumeric character is detected in any field (i.e. node name, peer name, description), the error will show. Commas and periods are common triggers of this bug. Try removing non-alphanumeric characters from any fields, then re-submit your transaction.

Did this solve your problem?