On May 22, 2015, the PostgreSQL Global Development Group released an
update to all supported versions of PostgreSQL, including versions
9.4.2, 9.3.7, 9.2.11, 9.1.16, and 9.0.20. This update has a bug in
fsync logic which will cause some users' PostgreSQL servers to refuse to
restart after a crash, or after a restore from binary backup. Please
read our FAQ on this issue
(https://wiki.postgresql.org/wiki/May_2015_Fsync_Permissions_Bug) before
applying the update to your systems.
The PostgreSQL Project regrets the error. Another PostgreSQL update,
with this issue corrected, will be released soon.