fluent/fluentd · error · Fluent::ConfigError

Unsupported timezone '#{timezone}'

Error message

Unsupported timezone '#{timezone}'

What it means

Fluent::ConfigError raised by Fluent::Timezone.validate! (lib/fluent/timezone.rb:92) when the timezone string does not pass format validation. Fluentd accepts only fixed-offset forms like +09:00, -0600, +0000 (and UTC) — named zones like 'Asia/Tokyo' and abbreviations like 'JST' or 'PST' are not supported because it formats offsets without a tz database.

Source

Thrown at lib/fluent/timezone.rb:92

          return false
        else
          # Valid. The string was found in the timezone database.
          return true
        end
      else
        # Invalid. Timezone abbreviations are not supported.
        return false
      end
    end

    # Validate the format of the specified timezone.
    #
    # The implementation of this method calls validate(timezone) method
    # to check whether the given timezone is valid. When invalid, this
    # method raises a ConfigError.
    def self.validate!(timezone)
      unless validate(timezone)
        raise ConfigError, "Unsupported timezone '#{timezone}'"
      end
    end

    using IntegerExt

    # Create a formatter for a timezone and optionally a format.
    #
    # An Proc object is returned. If the given timezone is invalid,
    # nil is returned.
    def self.formatter(timezone = nil, format = nil)
      if timezone.nil?
        return nil
      end

      # [+-]HH:MM, [+-]HHMM, [+-]HH
      if NUMERIC_PATTERN === timezone
        offset = Time.zone_offset(timezone)

View on GitHub (pinned to dd45c6e18d)

Solutions

1. Replace the zone name/abbreviation with its fixed numeric offset, e.g. timezone Asia/Tokyo -> timezone +0900
2. Use exactly the supported shapes: +HH:MM, -HH:MM, +HHMM, or UTC
3. If records cross DST and need true zone awareness, convert times upstream or in a filter with tzinfo instead of the timezone option

Example fix

# before
<parse>
  @type nginx
  time_format %d/%b/%Y:%H:%M:%S %z
  timezone Asia/Tokyo
</parse>

# after
<parse>
  @type nginx
  time_format %d/%b/%Y:%H:%M:%S %z
  timezone +09:00
</parse>

require 'fluent/timezone'

Fluent::Timezone.validate!('+09:00')   # raises Fluent::ConfigError early if unsupported
# rule of thumb: only +HH:MM / -HH:MM / +HHMM / UTC pass; never zone names

When it happens

Trigger: Setting timezone Asia/Tokyo or timezone JST in a parser/formatter or <system>; validate! runs during configuration (called from TimeParameters#configure at time.rb:184 and elsewhere), so fluentd fails at startup/dry-run. Passing a malformed offset like '+9' or '09:00' without sign also fails.

Common situations: Porting configs from libraries that accept IANA zone names; writing timezone UTC+9 instead of +0900; assuming DST-aware zones work (they cannot — fixed offsets only); typos in the offset string.

Related errors

• specifying timezone requires time format
• both of utc and localtime are specified, use only one of the
• invalid number of workers (must be 1 or unspecified) with --
• <system> is duplicated. <system> should be only one
• time_type is :mixed but time_format and time_format_fallback

AI-assisted analysis of fluent/fluentd@dd45c6e18d (2026-08-21). Data as JSON: /api/errors/4c326df19320ab63. Report an issue: GitHub.