bad expires code - what does that mean?

[mikemwe]

I'm just getting into logs as a newbie, and I have no idea what this means. It appears often in my logs and I need some help to see what the problem is. Any assistance would be appreciated.

[jdMorgan]

Are you using mod_expires directives?

If so, then it's likely that the format for your Expires header is incorrect. See Apache mod_expires for the valid formats.

A common cause of your problem is to omit the "A" or "M" base specification from the expiry specification; e.g. trying to use

ExpiresDefault 7200

instead of the correct

ExpiresDefault A7200

or

ExpiresDefault Access plus 2 hours

Jim