我正在尝试将我的 PostgreSQL 9.4 数据库升级到 PostgreSQL 9.5，但每次运行时sudo pg_upgradecluster 9.4 main我都会收到此错误：
Stopping old cluster...
Disabling connections to the old cluster during upgrade...
Restarting old cluster with restricted connections...
perl: warning: Setting locale failed.
perl: warning: Please check that your locale settings:
LANGUAGE = "en_US.UTF-8",
LC_ALL = (unset),
LC_CTYPE = "UTF-8",
LANG = "en_US.UTF-8"
are supported and installed on your system.
perl: warning: Falling back to the standard locale ("C").
Error: The locale requested by the environment is invalid.
Error: Could …