This error arises from an issue with HMRC's MTD system and is entirely beyond the control of VT Software.
This error usually means that the sign up process for MTD for the business is not yet complete. When the process is complete you should receive a confirmation email. This can take up to 3 days.
If you believe that business is already signed up to MTD, you can check that this is the case by signing into the business's business taxes account as described in step 2. of Setting up MTD: businesses.
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 HMRC.
This error may also indicate that HMRC's MTD system is busy, in which case please try again later or early the next day. However we have generally found that this error is due to the MTD sign-up process being incomplete.
This error indicates HMRC's MTD service is not available due to maintenance, in which case try again a bit later.