The Logback manual states
In PatternLayout, parenthesis can be used to group conversion patterns. It follows that the '(' and ')' carry special meaning and need to be escaped if intended to be used as literals. The special nature of parenthesis is further explained below.
[...]
If you need to treat the parenthesis character as a literal, it needs to be escaped by preceding each parenthesis with a backslash. As in,
\(%d{HH:mm:ss.SSS} [%thread]\)
.
You'll need to escape the parenthesis with a \
.
%d{yyyy-MM-dd HH:mm:ss.SSS} [%thread] %-5level %logger{36}.%M\(%line\) - %msg%n