Restore Error: "The media set has X media families but only 1 are provided"

When trying to Restore a database, you may receive the following error:

"System.Data.SqlClient.SqlError: The media set has 2 media families but only 1 are provided. All members must be provided."

The Cause

This error occurs because the .bak file you uploaded is incomplete or structured incorrectly. This happens in two scenarios:

1. Split Backups: You created a backup that was split across multiple files (e.g., backup_part1.bak and backup_part2.bak), but you only uploaded one of them. Our system only supports single-file backups.
2. Appended Backups: You backed up your database to a file that already contained previous backups. This creates a "Media Set" containing multiple historical backups, which our simple restore tool cannot parse.

The Solution

You must recreate the backup file on your local computer before uploading it again.

1. Open SQL Server Management Studio (SSMS).
2. Right-click your local database and select Tasks > Back Up...
3. Important: Under the "Destination" section, click Remove to clear any existing file paths. Then click Add to create a brand new file.
4. Go to the Media Options tab.
5. Select Overwrite all existing backup sets.
6. Click OK to generate a clean, single-file backup.
7. Upload this new file to our server and try the restore again.