Due to a number of new acquiring bank connectors, Visa and Mastercard mandates for 3DS 2. 

There is a restriction for the length of the transaction ID. 

If you are making use of Peach Payments, take note of restriction on the transaction ID length - which can be set to a maximum of 16 characters. 

A transaction with a transaction ID longer than 16 characters will fail with the following error "transaction declined (format error) (800.100.156)"

Please see below an example of the above-mentioned` error:

Example of a POST Request that will FAIL:

This request below has more than 16 characters, and will therefore fail as above: 

The merchantTransactionId should be 16 characters or less