Why do I receive warning messages about the Toolbox Path Cache when starting MATLAB?

I receive some or all of the following warning messages when starting MATLAB:

\\System\MATLAB\toolbox\toolboxname not found in Toolbox Path Cache

Warning: MATLAB Toolbox Path Cache is out of date and is not being used.

Warning: Unable to load Toolbox Path Cache

I would like to know what these messages mean. I wonder if there is something wrong with the Toolbox Path Cache, and if MATLAB will still function properly.

Answer 1

[MathWorks Support Team]

The Toolbox Path Cache is a file that MATLAB uses to store information regarding the location of toolbox directories. It is used because loading the information from a single local file is quicker than accessing the file system, particularly when there are many toolboxes or the directories are being accessed across a network. The cache file will also be updated at the end of each MATLAB session. More information regarding the toolbox path cache is available here:

https://www.mathworks.com/help/matlab/matlab_env/toolbox-path-caching-in-the-matlab-program.html

Both error messages indicate that there is an issue with the current Toolbox Path Cache file. Generally both errors will be resolve by restarting MATLAB as it will generate a new Toolbox Path Cache. If the error does return there are two ways to reset the Toolbox Path Cache

1. Using the command:

>> rehash toolboxcache

2. From the MATLAB Desktop:

Open the Preferences GUI. For MATLAB 7.14 (R2012a) and earlier releases go to the File menu to Preferences. For MATLAB 7.14 (R2012b) and later releases go to the Home tab to Preferences. In the Preferences GUI, select the "General" tab. Click the "Update Toolbox Path Cache" button to reset the Toolbox Path Cache.

After the Toolbox Path Cache is reset, the error should not return on startup.

[Johannes Kalliauer]

Thanks @MathWorksSupportTeam!

I had a similar issue:

Warning: Unable to load Toolbox Path Cache/home/lv71022/jkalliau/.matlab/R2018b/toolbox_cache-9.5.0-647392850-glnxa64.xml.The cache file is not in the correct format. It will be regenerated upon quitting MATLAB.

But it did not regenerate upon quitting. I run matlab -r "rehash toolboxcache" and now everything works. :-D