Isolating an issue by using another user account

Resolution

The issue at hand may simply be caused by a bad preference setting or user-specific data file. With proper isolation, you can avoid time-consuming and inappropriate troubleshooting methods.

About user accounts and troubleshooting

When you first set up a Mac, you go through the Setup Assistant to create a default administrator account for you, configured to automatically log in to the computer. You can later add additional user accounts via System Preferences. Each account has its own desktop, user-specific preference settings, and account-specific folders (described below).

In OS X, almost all the changes you make to settings for application as well as other data you create and modify are stored in your user account's Home folder ( /Users/your_account_name, also represented as ~/ ).

Here are some of the things that are stored in your user account's Home folder:

• All the files on your desktop.
• All the files in your Documents, Downloads, Movies, Music, Pictures, Public and Sites folders. 
• Any custom settings you have for applications such as Mail, Safari, Calendar (or iCal in OS X Lion and earlier), Finder, System Preferences, and other application settings you have modified, as well as third-party software settings.
• Mail data, iTunes data (music, books, movies, apps), Contacts (or Address Book in OS X Lion and earlier) contacts and groups, Safari bookmarks, Calendar (or iCal) calendars and events, iPhoto photos and movies, iMovie projects, third-party application data, and most files that you interact with.
   

When to troubleshoot with another user account

Testing with a new user isn't usually the first thing to do when isolating an issue, but should be tried before steps such as reinstalling applications, reinstalling OS X, or erasing the OS X disk.

If an issue occurs only when logged in to a specific user account, reinstalling the operating system or applications are not useful troubleshooting steps. If an issue does not occur when logged in to a new user account, then you know OS X and your installed applications are working as expected.

Troubleshoot with a test user account if...

• It is unclear whether or not the issue is limited to just one user account.
• The issue occurs after logging in a user account (that is, after your desktop appears).
• There is an Internet account-based issue in which it is unclear whether or not the issue is occurring just with your user or with the account itself. For example, local issues with iCloud, Exchange, third-party email, calendaring, chat, and synchronization services. Note: For issues that only occur in a  web browser, it's often best to test in multiple web browsers and with multiple websites, and then perform browser troubleshooting as necessary. If the issue occurs with multiple browsers or websites, consider testing with a different user account.

Do not troubleshoot with a test user account for...

• Any issue that occurs before the Login window or desktop appears.
• Physically damaged equipment, disconnected cables, and so forth.
• Issues that affect multiple computers. Note: An exception to this might be if you are using copied, synchronized or otherwise duplicated preferences or settings on multiple computers. For example, if you have migrated or restored the same user account to multiple computers, have manually copied settings between computers, and/or are using another service to sync preferences or keychains between computers.
• Internet account issues that occur with service-provider web applications, such as issues that are due to a site's service outage. For example, when a website is unavailable due to it being down or temporarily unavailable, but other websites work fine.

How to troubleshoot OS X user accounts

This process involves creating a new user account, logging in to it, and testing for the issue.

1. Create a new standard or admin user account in Users & Groups preferences. See this video, or this article for instructions for OS X Lion. See this article for instructions for OS X Mountain Lion.
2. Optional: If you have any specific files you wish to test with, copy (don't move) those items to the /Users/Shared folder in the Finder.
3. Log out of your current user account by choosing Log Out from the Apple () menu.
4. Log in with the new account you created.
5. Attempt to reproduce the issue you were seeing in your regular user account.
   
   Note: If you were using any specific settings that the issue depends on, such as using a specific email account, iCloud account, and so forth, then you should set up that account in System Preferences. For email and most other settings you should be able to set them up easily in the Mail, Contacts & Calendars System Preference pane. If you copied any files to the /Users/Shared folder that you need for testing, you would want to copy them to the desktop (or other applicable locations) of the test account.
    
6. Important: After you have completed testing, log out of the test account by by choosing Log Out from the Apple () menu.
7. Log in as your regular account.
8. After you have completed all testing with the test user account, you may wish to delete it. You can delete an account in the Users & Groups pane of System Preferences (Accounts preferences in Mac OS X v10.5 and 10.6) by simply selecting it and clicking the minus ("-") button below the account list. Note: Prior to deleting a test account, make sure you are completely done with it. If you have files in the Guest User you wish to keep, you should copy them to the /Users/Shared folder .
    

If the issue occurs in only one user account

If you have isolated an issue to a single user account, then you should focus your troubleshooting on that user and specific application(s) that are problematic when logged in as that user. Mac OS X: How to troubleshoot a software issue provides some assistance with this, although if you are just seeing the issue in one account, you most likely do not need to reinstall any applications.

Make sure you're using the most recent version of Mac OS X. If you're using a version of OS X Lion earlier than 10.7.4, see this article for assistance. 

If you are seeing issues with an application unexpectedly quitting in just one account, see this help article for additional assistance in OS X Lion. See this help article for additional assistance in OS X Mountain Lion.

Other, application-specific issues isolated to a single user account can often be caused by a problematic preference list or setting. Check the application's documentation or support website for instructions on troubleshooting specific preference or setting files. For example, iLife preference troubleshooting is documented in iLife: Troubleshooting Basics. If you are looking for assistance troubleshooting a specific alert message or issue, you should try searching the Apple Support website. 

If you need further assistance with troubleshooting an issue isolated to a specific user account, you may wish to contact Apple Support. If you work with AppleCare to troubleshoot the issue, be sure to let them know about any troubleshooting steps you have already performed and the results, and the text of any alert messages you have received. You may wish to take a screenshot of any messages (see this article for OS X Lion or this article for OS X Mountain Lion), so that you can use them for reference and provide them if needed.