恢复备份数据库(.bak文件)报错求助：指定的转换无效

Hey Anna, sorry to hear you're stuck on this SSIS tutorial step—let's break down how to fix that "Specified conversion is not valid" error when restoring the database backup.

Here are the most common causes and actionable fixes to get you back on track:

1. Mismatched SQL Server Versions #

The tutorial targets SQL Server 2017, so a version mismatch between the backup file and your local instance is the top suspect. Newer/older versions can throw conversion errors when restoring cross-version backups.

• Check your version: Open SSMS, right-click your server instance > Properties > General tab to confirm your SQL Server version number.
• Fix with T-SQL: If you're on a newer version, use this query to restore (adjust file paths and database name to match your setup):

  RESTORE DATABASE AdventureWorksDW2017
  FROM DISK = 'C:\Your\Download\Path\AdventureWorksDW2017.bak'
  WITH REPLACE,
  MOVE 'AdventureWorksDW2017' TO 'C:\Program Files\Microsoft SQL Server\MSSQL14.MSSQLSERVER\MSSQL\DATA\AdventureWorksDW2017.mdf',
  MOVE 'AdventureWorksDW2017_log' TO 'C:\Program Files\Microsoft SQL Server\MSSQL14.MSSQLSERVER\MSSQL\DATA\AdventureWorksDW2017.ldf';
  

  The WITH REPLACE flag overwrites conflicts, and WITH MOVE ensures files go to a valid path for your instance.

2. Corrupted Backup File #

Download glitches can corrupt the backup file, leading to conversion errors.

• Verify the backup: Run this query to check if the file is intact:

  RESTORE VERIFYONLY FROM DISK = 'C:\Your\Download\Path\AdventureWorksDW2017.bak';
  

  If it returns "The backup set is valid," the file is fine. If not, re-download the backup file from the tutorial resources.

3. Incorrect SSMS GUI Restore Settings #

If you're using the SSMS restore wizard, double-check these settings:

• Files tab: Ensure the "Restore As" paths point to a folder where your SQL Server has write access (default is usually C:\Program Files\Microsoft SQL Server\MSSQLXX.MSSQLSERVER\MSSQL\DATA\).
• Options tab: Check "Overwrite the existing database (WITH REPLACE)" to avoid conflicts with any existing databases of the same name.
• Recovery state: Leave it set to "RESTORE WITH RECOVERY" (default) so the database is usable immediately after restore.

4. Permissions Issue #

Your SSMS account or SQL Server service account might lack permissions to write to the data/log file locations.

• Fix: Run SSMS as an administrator, or confirm the SQL Server service account has read/write access to the target folder.

If none of these resolve the error, share the exact steps you took (GUI vs. T-SQL, any custom settings you changed) and the full error message text—this will help narrow down the issue further.

内容的提问来源于stack exchange，提问作者Anna