 I'm annoyed by your startup disk is almost full message. To resolve this issue, let us first know, what startup disk on Mac? Startup disk is a partition of internal hard drive, where OS data is stored, including documents, pictures, music, movies and apps. So, when we notice error message that your startup disk is almost full, means our hard drive has ran out space and is full. Well, there are two simple methods to fix your startup disk as full error message. First one is by using tuneupmymac application. Open Safari. Go to Sistweek website. Navigate to the products page. Scroll down to find tuneupmymac. Tap on free download button to download the product. Now, open setup file and follow the wizard to install tuneupmymac. Under installation, click on start system scan. Wait for the system to be scanned. Once, scanned, tap on clean now button to get rid of unwanted junk files and recover precious disk storage. Congratulations. All items cleaned. Second way to fix startup disk is almost full error message is by doing it manually. First manual way is remove redundant files and programs that are not used either regularly or anytime in the long term. For this, go to the finder. Here, sort files by file size, which will sort the files in descending order of size. Select the unused and unnecessary files and move them to trash. Now, we need to clean up trash as well. For this control plus click on trash icon. Select empty trash. To permanently erase all the items from the trash, tap on empty trash button. Second manual way is to run disk utility. For this, in finder, go to applications. Search for disk utility and open it. Here we can see the space used by wall types of file formats. To recover disk storage space, select the disk and run first aid. This will check and repair the errors. After first aid process is complete, we can see that some disk space has been recovered by running disk utility. However, manual methods could be time consuming, in that case we recommend you use tune up my mac, a complete carry utility for mac.