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SQL Server error code

SQL Server error 5120

SQL Server raises error 5120 at severity 16, which marks a problem with the query or data that you can correct.

Unable to open the physical file "%.*ls". Operating system error %d: "%ls".
Msg5120
NameDSK_FCB_FAILURE
Severity16
Group5000–5999

What it means

SQL Server was unable to open a database file. The operating system error provided in the message points to more specific underlying reasons for the failure. You may commonly see this error together with other errors like 17204 or 17207.

Source: Database Engine events and errors