Paul Randal notes a bug in SQL Server 2014:
I’m seeing reports from a few people of DBCC CHECKDB reporting PFS corruption after an upgrade from SQL Server 2014 to SQL Server 2016 or later. The symptoms are that you run DBCC CHECKDB after the upgrade and get output similar to this:
Msg 8948, Level 16, State 6, Line 5Database error: Page (3:3863) is marked with the wrong type in PFS page (1:1). PFS status 0x40 expected 0x60.Msg 8948, Level 16, State 6, Line 5Database error: Page (3:3864) is marked with the wrong type in PFS page (1:1). PFS status 0x40 expected 0x60.CHECKDB found 2 allocation errors and 0 consistency errors not associated with any single object.CHECKDB found 2 allocation errors and 0 consistency errors in database 'MyProdDB'.repair_allow_data_loss is the minimum repair level for the errors found by DBCC CHECKDB (MyProdDB).I’ve discussed with the SQL Server team and this is a known bug in SQL Server 2014.
Read on for the fix and additional good advice.