Error reading ICAP request headers
search cancel

Error reading ICAP request headers


Article ID: 160361


Updated On:


Data Loss Prevention Network Prevent for Web


If McAfee Web Gateway 7.1.6 is being used as a Proxy and AD Groups are enabled on it, end users may experience performance issues (web pages opening very slow or sometimes not able to browse internet) while browsing internet.

FileReader.log on Network Prevent for Web may have following Warning :

"WARNING: On ICAP connection ID=15982 unrecoverable error: Error reading ICAP request headers. Closing this connection."


Additionally, the McAfee Web Gateway may also show following Error Message :

"(16002) ICAP Client filter error: ICAP server send bad response"


Product Data Loss Prevention Network Prevent for Web


  1. In the Server Settings for Network Prevent for Web, increase the value of ICAP.BufferSize from 3k (default) to 5k.
  2. Clear and re-create the AD Groups on the McAfee Web Gateway.

Additional Information

Other circumstances may generate the same "request header" error reported above.

If users experience the following in their browsres "An ICAP error was encountered while handling the request", it's also possibly a "service overloaded" situation where performance sizing and tuning is required. If so, see Web Prevent Returning "503 Service Overloaded" to Upstream ICAP Client (