The 10th edition of Solomons was published around 2013. Many "free" PDFs circulating online are actually corrupted scans of the 8th or 9th edition. Using the wrong solutions manual is worse than using none, because the problem numbers and chemical structures change between editions.
Never open the solutions manual the moment you get stuck. Struggling with a problem is where the learning happens. Neurologically, the frustration of trying to recall a mechanism strengthens neural pathways. If you look up the answer immediately, you rob your brain of the chance to build that connection. The 10th edition of Solomons was published around 2013