Error Massage: “Operation must use an updateable query"

In MS Access, sometimes this error massage with error number 2950 may be a problem. It might be permission issue (see http://www.mikesdotnetting.com/Article/74/Solving-the-Operation-Must-Use-An-Updateable-Query-error), or an update from issue from joined table. For later, try following method to see if it does work:

UPDATE table SET field = 3
WHERE keyfield IN(SELECT keyfield FROM query)
;

It also can be caused by calculation within the UPDATE query. In this case, the best possible solution is to calculate before save into a temp table, then to join that temp table to get the calculated result.