New submission from David Bereza : Documentation link: https://docs.python.org/3/library/logging.config.html#configuration-file-for... It seems that the example for the "formatter_form01" formatter section specifies following for the style(please note the single-quotes around the value). style='%' This seems to raise a ValueError with the message "Style must be one of..." when parsing the configuration file. Removing the single quotes seems to fix the issue: style=% ---------- assignee: docs@python components: Documentation messages: 409108 nosy: bokunogf, docs@python priority: normal severity: normal status: open title: Incorrect format specified for the "style" key in the configuration file format formatter example versions: Python 3.8 _______________________________________ Python tracker https://bugs.python.org/issue46168 _______________________________________