When install fails, read the message first: permission, space, file in use or blocked. Each has its own fix. Below are the most frequent cases.
Permissions and file locks
On a permission error run as administrator; on a file-in-use error quit the running browser or reboot before installing.
- Right-click and run as administrator
- Quit running browser processes
- Reboot and retry if needed
- Avoid directories that need special rights
Space and paths
Make sure the target disk has at least 500 MB free and that the install path has no special characters or excessive depth.
- Keep at least 500 MB free
- Avoid special characters in the path
- Do not install into temp or synced folders
- Try a different disk
Security software
Some security products flag installers and quarantine them. Add the installer to the trust list, or download it again from the official site.
- Add the installer to the trust list
- Re-download from the official site
- Temporarily disable real-time protection
- Verify the installer SHA256 checksum
FAQ
Does a repair install delete my data?
No. It replaces program files only; bookmarks, passwords and settings live in your user data directory.
It says a newer version is already installed — what now?
That means this machine already has a newer build, so nothing to do. To start over, uninstall first.