I am getting an error on an old cgi script that is stopping the site after moving it from suse to RHEL Please take a look and if anybody know this I would appreciate your help 
[Thu Apr 13 15:13:45 2017] [error] [client 10.0.0.5] Template process 
+failed for page 'WS_advanced.tt' undef error - conv_perc: filter not 
+found, referer: http://server.my-site.com/Worksite/WS_advanced.cgi
[Thu Apr 13 15:15:22 2017] [error] [client 10.0.0.5] Template process 
+failed for page 'WS.tt' undef error - conv_perc: filter not found, re
+ferer: http://server.my-site.com/Worksite/WS.cgi

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The listed cgi scripts call matching templates and the lines that are causing the problem are here: 
grep -n conv_perc *.tt
WS_advanced.tt:318: [% item.swishreccount %]. <a href="[% item.swishdo
+cpath_href | replace ('^','http://')%]">[% ( item.swishtitle || item.
+swishdocpath )  %]</a><span class="smaller">-- rank: <span class="bol
+d">[% item.swishrank | conv_perc %]%</span></span><br>
WS.tt:319: [% item.swishreccount %]. <a href="[% item.swishdocpath_hre
+f | replace ('^','http://')%]">[% ( item.swishtitle || item.swishdocp
+ath )  %]</a><span class="smaller">-- rank: <span class="bold">[% ite
+m.swishrank | conv_perc %]%</span></span><br>

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In reply to cgi script error help by Anonymous Monk

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