Since the CA/Browser Forums' Ballot 193 passed a few weeks ago, Certification Authorities are encouraged to reduce the maximum Validity Period for TLS Certificates to a lifecycle no greater than 825 days (27 months), as of March 1st, 2018. The reason behind their immediate action is the paragraph BR 6.3.2:
Ballot 193, BR 6.3.2
Therefore, TLS Certificates with a Validity Period of 36 or more months, which have been issued between July 1st, 2016 and March 1st, 2018 are possibly running into trouble, if they will be reissued on/after March 1st, 2018. To mitigate the impact of shortened Validity Periods and to prevent mis-issuances on/after March 1st, 2018, Certificate Authorities decided to take immediate action. In return for the Certification Authority's immediate actions, CertCenter has also reduced TLS Certificates' maximum Validity Period to 24 months.