MTD - Current issues    
INTERNAL_SERVER_ERROR
This error arises from an issue with HMRC's MTD system and is entirely beyond the control of VT Software.

This error may indicate that HMRC's MTD system is busy. Please try again later or early the next day. Only a specific minority of businesses appear to suffer, but for them the error can occur repeatedly on a particular day.

This error may also indicate the user has signed up for MTD but HMRC have not yet completed the process. This can take up to 72 hours. Please see Preparing for MTD for VAT (businesses) or Preparing for MTD for VAT (agents).

If there is any possibility for confusion, please check the correct business is open in VT and check the VAT number.

If the error persists, please contact the HMRC online services helpdesk.

SERVER_ERROR
This error indicates HMRC's MTD service is not available due to maintenance.

Invalid Json
This error occurs if the VAT return contains amounts less than 1 but more than zero. To resolve this problem, please install the latest version of VT.
VT Software>Topics>MTD>Current issues