Discord's installer is a small bootstrapper that downloads and assembles the real app. When setup ends with 'installation has failed,' the most common reason is remnants of a previous Discord installation, folders the uninstaller left, a running process, or security software, colliding with the new setup. Clearing the remnants completely, then installing fresh, resolves the great majority of cases.
Discord folder from both %appdata% and %localappdata% (type those paths into the Explorer address bar). This is the step that makes the difference.Installers verify and overwrite; they are bad at resolving folders that are half-old and half-new, locked by processes, or owned by odd permissions. Discord's app data is sizable (cache, modules, update staging), so the odds of a leftover conflict are higher than with small apps. The clean-slate approach works because it removes the negotiation entirely.
The installer fails at the same percentage every time. A consistent stopping point usually means a specific file cannot be written, locked, quarantined, or out of space. The leftover cleanup plus an antivirus pause addresses the first two; check the drive has several gigabytes free for the third.
Is there an alternative to the standard installer? Discord offers a public test build (PTB) and a Canary build with separate installers and folders. They are useful diagnostics, if Canary installs, your profile and network are fine and the stable install's remnants were the issue.