Video Tutorial

Prefer a visual walkthrough? There's a video demonstrating the entire process. [VIDEO]

The Problem: Why Won't It Launch?

This tutorial applies to versions from Warlords of Draenor (WoD) and beyond. In this example, I am using the Firestorm Legion client.

If you try to start wow.exe while offline, you might get an error message saying "World of Warcraft could not resolve the address of the network data source."

Why does this happen? Every time you launch the game client, it attempts to fetch two tiny files from a remote Content Delivery Network (CDN):

versions: Checks if the client needs an update.
cdns: Contains URLs for downloading game data.

If these files cannot be reached, the client stops. To fix this, we must trick the client into downloading these files from your own computer (Localhost).

Prerequisites

Hex Editor: HxD (Recommended) or any similar tool.
Local Web Server: XAMPP (or any minimal HTTP server).
The Files: You need valid versions and cdns files for your specific game build.

Step 1: Open the Executable

The first step is to open your wow.exe with your Hex Editor. Once open, press Ctrl+F (or go to Find) and search for the text string: cdns.

If you go to the versions and cdns URLs in your browser, it will automatically download these files. If they don't start automatically, open your downloads manager and allow them. (Note: If you are using a mini-client, the uploader may have already included a backup of these files).

Step 2: Modify the URLs

Now we need to modify the URLs inside wow.exe to point to our local server (127.0.0.1).

On the right side of the Hex Editor (the text column), click on the first letter of the HTTP link.
Type the new link: http://127.0.0.1/cdns.
Critical Rule: The new URL cannot be longer than the original. It can be shorter, but you must overwrite the remaining characters of the old URL with Null Bytes.
- To do this: Click the corresponding cell in the Hex Column (left side) and type 00 for every extra character you need to erase.

Step 3: Local Server Setup (XAMPP)

Now, move the versions and cdns files you downloaded into your local web server.

If using XAMPP, place them inside the root directory: xampp/htdocs.

Once the files are in place and the modified wow.exe is in your game folder:

Open the XAMPP Control Panel.
Click Start next to Apache.
Your files should now be reachable at 127.0.0.1/versions and 127.0.0.1/cdns.

Special Case: The War Within (TWW)

Since The War Within (11.x), the URL structure inside the executable is different. Instead of a direct link, it uses placeholders (%s).

The Structure: https://%s.version.battle.net/v2/products/%s/%s

1st %s: Game Region (US, EU, CN, etc.)
2nd %s: Branch (wow, wow_classic, wow_beta, etc.)
3rd %s: File Type (versions or cdns)

Reference: Blizzard Backup URLs

Here are the direct links to backup the versions and cdns files from Blizzard servers. You can use these to verify your local setup.

US Retail

https://US.version.battle.net/v2/products/wow/versions
https://US.version.battle.net/v2/products/wow/cdns

US Classic

https://US.version.battle.net/v2/products/wow_classic/versions
https://US.version.battle.net/v2/products/wow_classic/cdns

EU Retail

https://EU.version.battle.net/v2/products/wow/versions
https://EU.version.battle.net/v2/products/wow/cdns

EU Classic

https://EU.version.battle.net/v2/products/wow_classic/versions
https://EU.version.battle.net/v2/products/wow_classic/cdns

Note: Private servers like Firestorm use their own CDN. They backed up these files and modified the cdns file to point to their own servers. For this offline fix, you generally do not need to modify the content of the cdns or versions files—just host them.

World of Warcraft - Other