Example config : <VirtualHost *:80> # ... # (standard stuff) # ... SetOutputFilter proxy-html <LocationMatch \.png$> SetOutputFilter none </LocationMatch> </VirtualHost> Currently, this produce the following message : [error] an unknown filter was not added: none Could the error message be avoided? (I know mod_filter is the recommanded way, but the configuration is harder) NB: see also #14335