Has anyone had success freezing a simple fruit filling (made with sugar and cornstarch). I have some left over and don't want to waste it.

Give it a try, you have nothing to lose and then will know for next time.

ADid you have any luck? I was about to post the same thing.

It won't work. I prefer to make a fruit mousse with fruit pieces in it, using gelatin to set. That holds up perfectly to freezing and thawing.

I have frozen raspberry filling and it freezes very nicely.  I made a huge amount for a big cake with additional kitchen cakes.  Since it has to strain for hours, I didn't want any last minute shortages, and I had almost 2 quarts left over.   Hated to throw that much away, and had nothing to lose, so I froze it.  The recipe I use is the cake boss recipe which is frozen raspberries, sugar, lemon juice and cornstarch and liqueur.  I froze it in containers with snap on lids (like those used at the deli for salads).  I used it all up within 3 months, and when defrosted, it was perfect.  I haven't tried it with other fruit fillings, but It seems like it should work if it is the same cornstarch/sugar base.   My lemon curd recipe says specifically not to freeze, so I haven't tried that either.  Let us know what you find out!