If at any point you need to downgrade your version of diablo back to 1.13 or lower after downloading 1.14a, if you previously had 1.13c or lower installed, follow this guide.

Again if you had not initially downloaded 1.14a as your base, you have nothing to worry about.

D2SE will not work if you did a fresh 1.14a install.1.14a will now be the default digital download for Diablo II. If you had 1.13c or lower installed initially, you won't come across this issue. Downloading Diablo II 1.14a fresh from Blizzards website (no prior version) will cause trouble with successfully downgrading your game to 1.13c or lower (a blank error).Created new German installers to fix localization issues in Act V (Will require a fresh install to fix the missing dialogue data) Capped the frame rate to 200 to save batteries, spare system load, and prevent hot lap syndrome Fixed Mac client crash on “Save & Exit” Mercenaries will no longer become “An Evil Force” Glide Wrapper will now load properly on PC by adding -3dfx to the end of the game shortcut First client run will migrate saved characters to avoid issues from Windows system Mac installer and compatibility for 10.10 and 10.11 has arrived

No need to run in XP mode anymore, Windows 7, 8.1, and 10 compatibility complete

Diablo 2 1.14 patch notes