NA:
There are plans to release Micropatch 0.9.20_4 on September 27th, 2017
Maintenance will begin at 03:30 Pacific Time (10:30 UTC) and will last approximately one hour and thirty minutes.
During maintenance, World of Tanks servers may become unavailable, however you should still be able to login and play.
EU:
Due to the micropatch World of Tanks servers will be unavailable on 27.09.2017:
WoT both EU servers – 4:30 UTC (06:30 CEST)
WoT Eu 1 – 5:00 UTC (07:00 CEST)
WoT Eu 2 – 5:30 UTC (07:30 CEST)
Each restart will take approximately 25 minutes.
No patch notes, only bugfixes.