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SQL Server error code

SQL Server error 2533

SQL Server raises error 2533 at severity 16, which marks a problem with the query or data that you can correct.

Table error: page %S_PGID allocated to object ID %d, index ID %d, partition ID %I64d, alloc unit ID %I64d (type %.*ls) was not seen. The page may be invalid or may have an incorrect alloc unit ID in its header.
Msg2533
NameDBCC_PAGE_WAS_NOT_SEEN
Severity16
Group2000–2999

What it means

A page is allocated to the allocation unit ID, A_ID, but this allocation unit ID is not in the header of the page. The header has a different allocation unit ID. If the allocation unit ID in the header of the page is for a valid object, the page may have a matching MSSQLEngine_2534 error.

Source: Database Engine events and errors