This happens all the time using ADO and recordset updates. It might work perfectly with thousends of records, and then suddenly out of nowhere exactly what you explain will happen.

We have a "huge" database system based on MySQL database (last two versions) using MyODBC (last three versions). Our largest customer have over 2 million table updates every day...

Using recordset updates we fast discovered that there is no logic when your problem will occur. Only solution that always works is to never use recordset updates. Instead you should use connection SQL execute like this: oCon.Execute "UDPATE arapk SET jnsfrm = '" & var1 & "', tglapk = '" & var2 & "' WHERE apknum = " & apknum & ";"

You will still have to use recordset to do the "if oRS.EOF then" check.

I also highly recommend you to not use recordset addnew too... use instead the following: oCon.Execute "INSERT INTO arapk (jnsfrm, tglaps, ...) VALUES ('" & var1 & "',' & var2 & ",...);"

If you need to know what autoincrement value your insert got use this immediately after:

Dim lngAutoID As Long lngAutoID = GetLastInsertID(oCon)

Public Function GetLastInsertID(dbConn As ADODB.Connection) As Long Dim rsLastInsertID As New ADODB.Recordset rsLastInsertID.Open "SELECT LAST_INSERT_ID()", dbConn, adOpenKeyset, adLockOptimistic GetLastInsertID = rsLastInsertID![LAST_INSERT_ID()] rsLastInsertID.Close End Function