LOGIC PRO X error (the doc. "x" could not be saved)

(PROBLEM) i wanted to work on some mixes and when i wanted to save on the already existing session, it tells me "THE DOCUMENT "X" COULD NOT BE SAVED .i simply couldn't save it. im capable of saving a new project but only once. after that, its the same error.i can also save as but the same issue happens if i try to do a normal save. ive seen people with a different issue where the save n save as we're greyed out but, it isn't the issue here. i work off my xternalHD which has plenty of space and i even tried to make a session on my mb HD which also has plenty of space left but, still nothing.really need help if anyone has any idea what could be happening PLEASE reply. thank you!