I've never had this happen to me before since my first time to attempt ever in making bread. When I was kneading the dough I noticed it was really stiff . I've used this same formula for a whole year every week without a single problem and with a cold kitchen (17C) Process of a (66% hydrated dough) 1) heat milk up to 185 f ( this time I used a new thermometer and I noticed there was an air bubble) 2) added orange juice to the total amount of milk (85%milk/15% orange juice) 3) had a 60/40 mixture flour of coarse whole wheat (18% protein) and white flour (15%) which makes it into 16.8% protein level. 4)added sugar to the liquid mixture( fairly warm at this stage 5)added the flour into the liquid and mixed till incorporated 6) 40 min autolayse 7) kneaded in sour dough starter and salt 5 min kneading (noticed it was really stiff right from the start) 9) gave it a 10 min rest hopefully to let the gluten relax 10) 15 min kneading and added butter during the time and added some warm water (still stiff as hell) 11) did not even come close to passing the windowpane test 12) shaped it into a ball and stuck it into my homemade retarder ( cooler) What could have caused such a stiff dough? I confirmed with another thermometer that the new thermometer was off so I did infact did not heat the milk to 185F ( which apparently destroys an enzyme that inhibits gluten development but is also controversial since some made great breads without heating it up.) just plain bad flour? Liquid too hot and slightly cooked the flour? Mixing in flour into the liquid( first time trying it this way)? I highly doubt this will have a good rise but I'll try bake it anyways. Maybe one of those weird moments things just don't work out .