This is for official servers:

https://steamcommunity.com/sharedfiles/filedetails/?id=1633731126

If you want to host a local server versus game, edit file Left 4 Dead 2\left4dead2\cfg\addonconfig.cfg and change all 1 to 0 to unblock add-ons in Versus, Scavenge and Versus Survival.

Originally posted by ion:

This is for official servers:

https://steamcommunity.com/sharedfiles/filedetails/?id=1633731126

If you want to host a local server versus game, edit file Left 4 Dead 2\left4dead2\cfg\addonconfig.cfg and change all 1 to 0 to unblock add-ons in Versus, Scavenge and Versus Survival.

i did what exactly you said but i cant join t1 lobbies after this. (sirplease)
"server is enforcing consistency for this file : left4dead2/gameinfo.txt "

how can i fix it as how it used to be? i prefer to play zonemode instead of having vocalizer in versus

This is from Questions & Answers section of the guide, in case you missed it:

• Will this work on all servers?
  No, this method is specifically for official Valve servers.

Regarding 3rd-party dedicated servers, some will allow this method and some will not (by enforcing consistency on gameinfo.txt file). You can't know until you try joining the server. Not much you can do about it, if anything, because it's totally up to server admins what will they allow on their private servers.

How to revert the change? Return the original gameinfo.txt. In case you haven't made a backup of it, verify integrity of game files and Steam will re-download the original.

Originally posted by ion:

This is from Questions & Answers section of the guide, in case you missed it:

• Will this work on all servers?
  No, this method is specifically for official Valve servers.

Regarding 3rd-party dedicated servers, some will allow this method and some will not (by enforcing consistency on gameinfo.txt file). You can't know until you try joining the server. Not much you can do about it, if anything, because it's totally up to server admins what will they allow on their private servers.

How to revert the change? Return the original gameinfo.txt. In case you haven't made a backup of it, verify integrity of game files and Steam will re-download the original.

thanks for informing me. i have undone the things what i have done for vozalizer. i can join sirplease again.

if your having consistency problems go into the console and type "sv_consistency 0" without the quotes.