Save guys,
I'm also having the same error.
I simply want to change the / knife command to any other of my interest, and by making this change, I try to compile the warmod.sp file, and run into this error.
// warmod.sp
//
// C:\SERVER CSGO\steamcmd\steamapps\common\Counter-Strike Global Offensive Beta - Dedicated Server\csgo\addons\sourcemod\scripting\warmod .sp(699) : error 017: undefined symbol "CHAT_PREFIX"
// C:\SERVER CSGO\steamcmd\steamapps\common\Counter-Strike Global Offensive Beta - Dedicated Server\csgo\addons\sourcemod\scripting\warmod .sp(699) : error 072: "sizeof" operator is invalid on "function" symbols
// C:\SERVER CSGO\steamcmd\steamapps\common\Counter-Strike Global Offensive Beta - Dedicated Server\csgo\addons\sourcemod\scripting\warmod .sp(906) : error 017: undefined symbol "CHAT_PREFIX"
// C:\SERVER CSGO\steamcmd\steamapps\common\Counter-Strike Global Offensive Beta - Dedicated Server\csgo\addons\sourcemod\scripting\warmod .sp(1055) : error 017: undefined symbol "CHAT_PREFIX"
// C:\SERVER CSGO\steamcmd\steamapps\common\Counter-Strike Global Offensive Beta - Dedicated Server\csgo\addons\sourcemod\scripting\warmod .sp(1122) : error 017: undefined symbol "CHAT_PREFIX"
// C:\SERVER CSGO\steamcmd\steamapps\common\Counter-Strike Global Offensive Beta - Dedicated Server\csgo\addons\sourcemod\scripting\warmod .sp(1230) : error 017: undefined symbol "CHAT_PREFIX"
// C:\SERVER CSGO\steamcmd\steamapps\common\Counter-Strike Global Offensive Beta - Dedicated Server\csgo\addons\sourcemod\scripting\warmod .sp(1234) : error 017: undefined symbol "CHAT_PREFIX"
// C:\SERVER CSGO\steamcmd\steamapps\common\Counter-Strike Global Offensive Beta - Dedicated Server\csgo\addons\sourcemod\scripting\warmod .sp(1246) : error 017: undefined symbol "CHAT_PREFIX"
// C:\SERVER CSGO\steamcmd\steamapps\common\Counter-Strike Global Offensive Beta - Dedicated Server\csgo\addons\sourcemod\scripting\warmod .sp(1250) : error 017: undefined symbol "CHAT_PREFIX"
// C:\SERVER CSGO\steamcmd\steamapps\common\Counter-Strike Global Offensive Beta - Dedicated Server\csgo\addons\sourcemod\scripting\warmod .sp(1273) : error 017: undefined symbol "CHAT_PREFIX"
// C:\SERVER CSGO\steamcmd\steamapps\common\Counter-Strike Global Offensive Beta - Dedicated Server\csgo\addons\sourcemod\scripting\warmod .sp(1277) : error 017: undefined symbol "CHAT_PREFIX"
// C:\SERVER CSGO\steamcmd\steamapps\common\Counter-Strike Global Offensive Beta - Dedicated Server\csgo\addons\sourcemod\scripting\warmod .sp(1286) : error 017: undefined symbol "CHAT_PREFIX"
// C:\SERVER CSGO\steamcmd\steamapps\common\Counter-Strike Global Offensive Beta - Dedicated Server\csgo\addons\sourcemod\scripting\warmod .sp(1290) : error 017: undefined symbol "CHAT_PREFIX"
// C:\SERVER CSGO\steamcmd\steamapps\common\Counter-Strike Global Offensive Beta - Dedicated Server\csgo\addons\sourcemod\scripting\warmod .sp(1315) : error 017: undefined symbol "CHAT_PREFIX"
// C:\SERVER CSGO\steamcmd\steamapps\common\Counter-Strike Global Offensive Beta - Dedicated Server\csgo\addons\sourcemod\scripting\warmod .sp(131
: error 017: undefined symbol "CHAT_PREFIX"
// C:\SERVER CSGO\steamcmd\steamapps\common\Counter-Strike Global Offensive Beta - Dedicated Server\csgo\addons\sourcemod\scripting\warmod .sp(1319) : error 017: undefined symbol "CHAT_PREFIX"
// C:\SERVER CSGO\steamcmd\steamapps\common\Counter-Strike Global Offensive Beta - Dedicated Server\csgo\addons\sourcemod\scripting\warmod .sp(1339) : error 017: undefined symbol "CHAT_PREFIX"
// C:\SERVER CSGO\steamcmd\steamapps\common\Counter-Strike Global Offensive Beta - Dedicated Server\csgo\addons\sourcemod\scripting\warmod .sp(1342) : error 017: undefined symbol "CHAT_PREFIX"
// C:\SERVER CSGO\steamcmd\steamapps\common\Counter-Strike Global Offensive Beta - Dedicated Server\csgo\addons\sourcemod\scripting\warmod .sp(1343) : error 017: undefined symbol "CHAT_PREFIX"
// C:\SERVER CSGO\steamcmd\steamapps\common\Counter-Strike Global Offensive Beta - Dedicated Server\csgo\addons\sourcemod\scripting\warmod .sp(1376) : error 017: undefined symbol "CHAT_PREFIX"
// C:\SERVER CSGO\steamcmd\steamapps\common\Counter-Strike Global Offensive Beta - Dedicated Server\csgo\addons\sourcemod\scripting\warmod .sp(1385) : error 017: undefined symbol "CHAT_PREFIX"
// C:\SERVER CSGO\steamcmd\steamapps\common\Counter-Strike Global Offensive Beta - Dedicated Server\csgo\addons\sourcemod\scripting\warmod .sp(138
: error 017: undefined symbol "CHAT_PREFIX"
// C:\SERVER CSGO\steamcmd\steamapps\common\Counter-Strike Global Offensive Beta - Dedicated Server\csgo\addons\sourcemod\scripting\warmod .sp(1406) : error 017: undefined symbol "CHAT_PREFIX"
// C:\SERVER CSGO\steamcmd\steamapps\common\Counter-Strike Global Offensive Beta - Dedicated Server\csgo\addons\sourcemod\scripting\warmod .sp(1416) : error 017: undefined symbol "CHAT_PREFIX"
// C:\SERVER CSGO\steamcmd\steamapps\common\Counter-Strike Global Offensive Beta - Dedicated Server\csgo\addons\sourcemod\scripting\warmod .sp(1419) : error 017: undefined symbol "CHAT_PREFIX"
// C:\SERVER CSGO\steamcmd\steamapps\common\Counter-Strike Global Offensive Beta - Dedicated Server\csgo\addons\sourcemod\scripting\warmod .sp(1429) : error 017: undefined symbol "CHAT_PREFIX"
//
// Compilation aborted.
// 26 Errors.
//
// Compilation Time: 0,86 sec
// ----------------------------------------