This guide will give you a quick rundown on how to generally fix any errors regarding Diablo II patch installation. When you come across a installation error normally part of the file has downloaded but then it encountered an error in the middle of the installation so what we need to do is locate, delete, and replace the patch file manually.

Step 1

Locate your Diablo II directory (where you installed the game) generally located in the Program Files folder within the C drive.

Step 2

Once you open your Diablo II directory you are going to look for your patch file. For me it is a .MPQ file named "patch_d2.mpq"



Once you locate your patch file you will delete it. (Make sure your Diablo game is not running)

Step 3

Once you delete your patch file you are going to re-download the patch file except from Blizzard's website instead of through Diablo II.

Go to this link for your patch download link: https://us.battle.net/support/en/article/diablo-ii-patch-information

The latest patch is 1.13 and you can download the most recent patch for either original or Lord of Destruction for both PC and MAC.

Step 4

After downloading your patch file you are going to place it back into your Diablo II folder. Run Diablo II, it should skip downloading the patch (since you already have the file) and go to "checking latest versions" and connect you to battle.net

Miscellaneous Information

You can also download previous patch versions for either original or Lord of Destruction for both PC and MAC. Although this would only be for single player use.

Diablo II Patch Index: http://ftp.blizzard.com/pub/diablo2/patches/

Diablo II: Lord Of Destruction Patch Index: http://ftp.blizzard.com/pub/diablo2exp/patches/

You can also simply switch patch versions by copying over/replacing your current patch file with another.

Conclusion

I have seen many users encounter patch installation problems and this method seemed to have done the trick. In the event that this does not resolve your issue send me a message and we can work together to fix it