A One time relaxation to update UDIN has been enabled. Kindly update the UDIN before 31st December, 2020 of audit report/certificates to avoid invalidation.

Source : https://taxguru.in/income-tax/cbdt-time-31st-december-2020-update-udin.html#:~:text=A%20One%20time%20relaxation%20to,report%2Fcertificates%20to%20avoid%20invalidation.