Seldaek/monolog · error · InvalidArgumentException

Invalid date format - format must be one of RotatingFileHand

Error message

Invalid date format - format must be one of RotatingFileHandler::FILE_PER_HOUR ("Y-m-d-H"), RotatingFileHandler::FILE_PER_DAY ("Y-m-d"), RotatingFileHandler::FILE_PER_MONTH ("Y-m") or RotatingFileHandler::FILE_PER_YEAR ("Y"), or you can set one of the date formats using slashes, underscores and/or dots instead of dashes.

What it means

Error "Invalid date format - format must be one of RotatingFileHandler::FILE_PER_HOUR ("Y-m-d-H"), RotatingFileHandler::FILE_PER_DAY ("Y-m-d"), RotatingFileHandler::FILE_PER_MONTH ("Y-m") or RotatingFileHandler::FILE_PER_YEAR ("Y"), or you can set one of the date formats using slashes, underscores and/or dots instead of dashes." thrown in Seldaek/monolog.

Source

Thrown at src/Monolog/Handler/RotatingFileHandler.php:217

            ['{filename}', '{date}'],
            [$fileInfo['filename'], str_replace(
                ['Y', 'y', 'm', 'd', 'H'],
                ['[0-9][0-9][0-9][0-9]', '[0-9][0-9]', '[0-9][0-9]', '[0-9][0-9]', '[0-9][0-9]'],
                $this->dateFormat
            )],
            ($fileInfo['dirname'] ?? '') . '/' . $this->filenameFormat
        );
        if (isset($fileInfo['extension'])) {
            $glob .= '.'.$fileInfo['extension'];
        }

        return $glob;
    }

    protected function setDateFormat(string $dateFormat): void
    {
        if (0 === preg_match('{^[Yy](([/_.-]?m)([/_.-]?d([/_.-]?H)?)?)?$}', $dateFormat)) {
            throw new InvalidArgumentException(
                'Invalid date format - format must be one of RotatingFileHandler::FILE_PER_HOUR ("Y-m-d-H"), '.
                'RotatingFileHandler::FILE_PER_DAY ("Y-m-d"), RotatingFileHandler::FILE_PER_MONTH ("Y-m") '.
                'or RotatingFileHandler::FILE_PER_YEAR ("Y"), or you can set one of the '.
                'date formats using slashes, underscores and/or dots instead of dashes.'
            );
        }

        $this->dateFormat = $dateFormat;
    }

    protected function getNextRotation(): \DateTimeImmutable
    {
        return match (str_replace(['/','_','.'], '-', $this->dateFormat)) {
            self::FILE_PER_MONTH => (new \DateTimeImmutable('first day of next month', $this->timezone))->setTime(0, 0, 0),
            self::FILE_PER_YEAR => (new \DateTimeImmutable('first day of January next year', $this->timezone))->setTime(0, 0, 0),
            default => (new \DateTimeImmutable('tomorrow', $this->timezone))->setTime(0, 0, 0),
        };
    }

View on GitHub (pinned to 57eb102834)

When it happens

Trigger: Thrown at src/Monolog/Handler/RotatingFileHandler.php:217 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of Seldaek/monolog@57eb102834 (2026-08-17). Data as JSON: /api/errors/09e32f8926e22cd9. Report an issue: GitHub.