Did you save your own seed? It may have crossed with something. If you bought it..same thing..maybe just bad seed this year. Next year, get seed from a reputable place and try again..as gardeners..that's what we do year after year! There's really nothing cultural that might have caused that...some years we win, some not!

Also...even picked too early...spaghetti squash still has the long strings..so it's not that, either.

Sounds exactly like the squash started to rot. When that happens, the seeds sprout, the structure inside turns to mush and the taste goes south. Were there any penetrations in the shell? Also, the shelf life of these is pretty short. Only a month or two, depending on conditions. If you picked them in early June, I'm guessing you're in a warm climate, and your pantry isn't that cool.

Yeah, in Texas.

I think that must be it..... they must be getting too old.