I have this error in http_plugin.log:
Wed Jan 20 12:02:36 2010 00010da8 00001314 - ERROR: ESI: getResponseFromCache: invalid If-Modified-Since header value: 0xffffffff
It repeats frequently but in a random fashion.
Extract from access_log file shows 304 codes many times indicating that the web server returns the content has no modifications. Eg:
184.108.40.206 - -
I tried to recreate the error with a java program but i couldn´t send http requests with wrong values in If-Modified-Since header.
Is this a problem related to older browsers that send http requests with bad headers?
Is this a problem related to http server or plugin configuration?
Thanks in advance for your suggestions.