I have tried to submit a VAT return today (which has always worked in the past) and it has failed. I am not signed up for MTD and I do not need to.
The message I got back from HMRC was: “The submission for reference xxxxxxxxxxx was received on 06/12/19. Unfortunately it could not be accepted as it failed HMRC data checks.” And the message I got from Quickfile was: “By ChRIS : The VAT Period you have entered 2019-09 for the VRN xxxxxxxxxx was not found, please check and resubmit if necessary.”
Other posts seem to suggest that this is because I am signed up for MTD and have not configured Quickfile, but I am not signed up for MTD.
I contacted HMRC and they could not see a problem their end and advised me to submit manually on this occasion which I did without issue. They also said there was no reason for me to sign up for MTD, and in fact, advised me not to!
From the error you pasted above, it looks like you were trying to submit it with a September date (2019-09) rather than October. This is probably why it was being rejected by HMRC.
You mentioned about submitting it manually above - have you done this successfully now?
Are you sure you have your vat settings correct? Quickfile asks to select the starting period for vat returns which can confuse people as usually software will ask for the ending period
Perhaps check your vat setting is showing the correct starting period.