How to use the Cache Rebuild tool to fix problems with your Mac

How to use the Cache Rebuild tool to fix problems with your Mac

As a Mac user, you may have come across a situation in which your Mac seems to be behaving strangely. If you’ve run the Intermediate Suite and haven’t discovered any issues, it might be an issue with your Mac’s various caches. With the Cache Rebuild Tool, you can target specific macOS caches to chase down more mysterious issues.

The Cache Rebuild tool includes options to rebuild several of your Mac’s caches. Read on to see if the problem you’re experiencing can be addressed with this specialized tool.

Boot Cache

Using the Cache Rebuild tool with the Boot Cache option enabled will forcefully rebuild the dynamic linker shared cache on macOS. The dynamic linker shared cache is a system file that contains a combined version of many commonly used system libraries. This cache is used to speed up the launch of applications by reducing the amount of disk I/O required to load these libraries.

System Updates or Software Installation: After a system update or the installation of new software, the shared cache might need to be updated to ensure that it includes the latest versions of libraries. While this is typically handled automatically by the system, you might use the Cache Rebuild Tool’s Boot Cache option to manually rebuild the cache if you suspect it has become corrupted or out of date.

Troubleshooting: If you’re experiencing issues with applications crashing on launch or behaving erratically, and you suspect that the problem might be related to the dynamic linker shared cache, you might use this option to forcefully rebuild the cache in an attempt to resolve the issue.

Performance Optimization: In some rare cases, you might use this option to optimize system performance if you believe that the dynamic linker shared cache is not functioning efficiently.

DNS Cache

You might need to use the Cache Rebuild tool to clear the DNS cache for several reasons, primarily related to resolving issues with cached directory service information on your Mac. Here are some common scenarios:

Slow or failing user authentication: If logging in to your Mac or authenticating to network services is slow or failing, it could be due to outdated or corrupt cache entries. Flushing the cache can refresh these entries and potentially resolve the issue.

Network resource access problems: If there are issues accessing network resources like shared folders or printers, it could be due to outdated cache entries. Flushing the cache with dscacheutil can help refresh the entries and resolve access problems.

Hostname resolution issues: Sometimes, your Mac might have trouble resolving hostnames to IP addresses, which can affect various network services. Rebuilding the DNS Cache can clear the DNS cache, potentially resolving these resolution issues.

Font Cache

The Font Cache option is for managing the Apple Type Services (ATS) font registration system on macOS. When you run the Cache Rebuild with this option selected, it deletes the font cache for the user who is currently logged in. This can be useful in the following scenarios:

Font display issues: If you’re experiencing problems with fonts not displaying correctly, such as missing characters or incorrect rendering, clearing the user font cache might resolve these issues.

Font conflicts: If you’ve installed new fonts and are experiencing conflicts with existing fonts, removing the user font database can help reset the font registration and eliminate conflicts.

Performance issues related to fonts: In some cases, a corrupt font cache can cause applications that use fonts heavily (like word processors or graphic design software) to perform poorly. Clearing the cache can sometimes improve performance.

After running the command, you may need to log out and log back in, or even restart your computer, for the changes to take effect. It’s also worth noting that this action only affects the font cache for the current user; it does not affect system-wide font caches or the font caches of other users on the same machine.

Dock Cache

Run the Cache Rebuild with the Dock Cache option selected to delete the Dock icon cache files. The Dock is a feature of macOS that provides quick access to applications, documents, and other items. Over time, the Dock’s icon cache can become outdated or corrupted, which can lead to issues such as missing or incorrect icons.

By deleting the icon cache files, you force the Dock to regenerate its cache the next time it is loaded. This can help resolve issues with icons not displaying correctly or updating properly.

The Cache Rebuild will restart the Dock in order for the changes to take effect. The Dock will automatically restart after being killed, and it will regenerate its icon cache using the updated or corrected icons.

*Note – The Cache Rebuild tool can also rebuild the Kernel Cache on Macs Running macOS 11, Big Sur, or earlier. The prelinked kernel is a file that combines the kernel with a set of kernel extensions (kexts) that are needed during the boot process. This prelinking helps speed up the boot process by reducing the amount of work needed to load and initialize the kernel and its extensions. Starting with macOS Big Sur, the system architecture has changed significantly, and the concept of a prelinked kernel has been replaced with a sealed System volume and snapshot-based updates. As a result the Kernel Cache option is not available on Macs running more recent versions of macOS.

The Cache Rebuild tool is a power tool to repair specialized parts of your Mac that commonly misbehave. Be sure to bookmark this page to check if an issue you’re experiencing with your Mac might be addressed by using this powerful tool.

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