Unrecognized error log format directive %U in Apache2 ErrorLogFormat

I created Apache2 ErrorLogFormat below:

ErrorLogFormat "[%t] [%-m:%-l] [client %a] [Path %U] [UA %{User-agent}i] %M"

But got the error when I tried to reload apache

Unrecognized error log format directive %U
Action 'configtest' failed.

Can I use the "%U" which is the path? or is there any alternative for this?