Once your game is on the correct version, you need to download the maps.
To prevent "Fatal Error" crashes, go to Options -> Video and set settings to high, but turn off shadows if you experience lag on older machines. Troubleshooting
To get started, you need the original base game files. Because Blizzard replaced classic installations with the Reforged launcher, you must rely on physical discs, backup ISO files, or trusted community archives. You will need: (The base game) Warcraft III: The Frozen Throne (The expansion pack) The 1.26a Version Switcher or Offline Patch Executable warcraft iii the frozen throne dota 126 install
Eurobattle.net maintains a server specifically for patch 1.26 and 1.28.
(like RGC or ICCup) that still support v1.26a. Fix "Fatal Error" crashes by adjusting registry settings. Configure custom hotkeys for older Dota versions. Once your game is on the correct version,
To install Warcraft III: The Frozen Throne on version for full featured DotA gameplay, you must first install the base game and its expansion before applying the standalone patch. This specific version is highly sought after because it supports classic private servers like GameRanger and legacy DotA maps that exceed 8MB. www.reddit.com Installation Steps
One of the most significant quality-of-life updates in the 1.2x era was removing the requirement for the physical CD to be in the drive. Fix "Fatal Error" crashes by adjusting registry settings
: Specifically the "Universal Patch" or the step-up patch to version 1.26a. 2. Step-by-Step Installation Guide
If you want to host a LAN party or play DotA 6.83d without lag, input delay, or script errors, you need patch 1.26.
How to Install Warcraft III: The Frozen Throne & DotA 1 (Patch 1.26a)