Why would i get a duplicate write error of auto-generated primary key? Hi I'm not a DBA so forgive my ignorance. I don't have access to administrator tools etc. However, I do know that we have a live server which is approaching capacity ie 80%-90% full perhaps.

What is happening is that our web-application has started not writing certain records and it appears as though SQLServer is attempting to write a duplicate primary key in certain tables. I don't understand this and as this is an auto-generated column it is completely out of our control.

Is this a possible symptom of the server getting too full? Surely a DBMS should manage this kind of thing safely?
I think this could happen only if manual intervention was done to that primary key. It's possible to manually insert data in the identity column only if option "set identity_insert table_name on" was used, that way you can generate PK errors.
But better check exactly if the PK is only that identity column, and, if yes, if this option is used in any of the stored procedures or scripts that you use.

SQL Server alone would not have any reason to not treat correctly these columns.