Right after installation Deepin OS without having any difficulties "System Update" can be prceed.  However after some days or months it cant be done as it was. I checked the network connections and all fine. But when I hit on the update button it does find the updats showing the progress bar. But right end of the progress bar, when almost search updates are done, suddenly stop there showing "Red cross" with text : "Check again". I dig the internet for a solution and got nothing. So any help in this regard is higly appriciated.