You don’t have permission to save the file “988BF072-A4B9-4ABE-9FB8-2F3A8EBC2E2C” in the folder “CoreSimulator”

Just finished solving this problem. I think the main issue is that you are looking in the wrong place. These are the steps I took:

1. Make hidden folders visible by going to terminal and executing these two commands:

   defaults write com.apple.finder AppleShowAllFiles TRUE
   
   killall Finder
   

2. Go to /Users/myUsername/Library now it should be visible ( instead of myUsername you should have yours)

3. The Logs folder has no access permission, so change it. In case you can't do it manually, go to 3b.

   3b. Open terminal. Write this command

   sudo chmod 777 ~/Library/Logs 
   

4. Be happy

P.S. In case you don't want to see hidden folder and files anymore, execute this two lines in terminal:

defaults write com.apple.finder AppleShowAllFiles FALSE

killall Finder

So your permissions are invalid. You should look in ~/Library/Logs/CoreSimulator and check what the ownership and permissions are set to and fix them.

If that doesn't work, update your question with explanation of what you tried and show the current ownership and permissions on the relevant paths.

Turns out the actual folder for the log file didn't exist.

When looking in Console.app, filtering on CoreSimulator, I saw this:

3/15/15 9:50:52.840 AM iOS Simulator[7291]: Error opening /Users//Library/Logs/CoreSimulator/iOS Simulator.log

When I went to the Logs directory, CoreSimulator wasn't there, so I:

sudo mkdir CoreSimulator
sudo chown <user>:staff CoreSimulator
touch CoreSimulator/iOS\ Simulator.log