License expired, deleted and re-download, now not working

My school's license expired on Monday. I deleted and re-downlaoded MATLAB with the new license. Now when I start the program, the below pops up in red. How do I get it to work now. I am using the same 2020b that I was already using with MacOS Catalina. Thank you.

Exception in thread "Startup Class Loader": java.lang.NoClassDefFoundError: Could not initialize class java.nio.file.FileSystems$DefaultFileSystemHolder

at java.nio.file.FileSystems.getDefault(FileSystems.java:176)

at java.nio.file.Paths.get(Paths.java:138)

at com.mathworks.instutil.InstutilResourceKeys.<clinit>(InstutilResourceKeys.java:74)

at com.mathworks.mlwidgets.help.DocCenterRoot.initDocRelease(DocCenterRoot.java:44)

at com.mathworks.mlwidgets.help.DocCenterRoot.<clinit>(DocCenterRoot.java:26)

at com.mathworks.mlwidgets.help.HelpPrefs.<clinit>(HelpPrefs.java:57)

at java.lang.Class.forName0(Native Method)

at java.lang.Class.forName(Class.java:264)

at com.mathworks.mlservices.MLHelpServices.getDocRoot(MLHelpServices.java:522)

at com.mathworks.mlwidgets.util.productinfo.ProductInfoUtils.getDocrootDirectory(ProductInfoUtils.java:707)

at com.mathworks.mlwidgets.util.productinfo.ProductInfoUtils.getAbsolutePath(ProductInfoUtils.java:694)

at com.mathworks.mlwidgets.util.productinfo.ProductInfoUtils.parseFile(ProductInfoUtils.java:259)

at com.mathworks.mlwidgets.util.productinfo.ProductInfoUtils.parseFiles(ProductInfoUtils.java:319)

at com.mathworks.mlwidgets.util.productinfo.ProductInfoUtils.pathChanged(ProductInfoUtils.java:154)

at com.mathworks.mlwidgets.util.productinfo.ProductInfoUtils.<init>(ProductInfoUtils.java:80)

at com.mathworks.mlwidgets.util.productinfo.ProductInfoUtils.getAllProductsInfo(ProductInfoUtils.java:900)

at com.mathworks.mlwidgets.util.productinfo.ProductInfoUtils.<clinit>(ProductInfoUtils.java:66)

at java.lang.Class.forName0(Native Method)

at java.lang.Class.forName(Class.java:264)

at com.mathworks.mde.desk.StartupClassLoader$LoadInfo.<init>(StartupClassLoader.java:112)

at com.mathworks.mde.desk.StartupClassLoader.createLoadInfos(StartupClassLoader.java:202)

at com.mathworks.mde.desk.StartupClassLoader.access$500(StartupClassLoader.java:25)

at com.mathworks.mde.desk.StartupClassLoader$2.run(StartupClassLoader.java:223)

at java.lang.Thread.run(Thread.java:748)

Exception in thread "ContributedToolsLoader": java.lang.NoClassDefFoundError: Could not initialize class java.nio.file.FileSystems$DefaultFileSystemHolder

at java.nio.file.FileSystems.getDefault(FileSystems.java:176)

at java.io.File.toPath(File.java:2234)

at com.mathworks.resources_folder.ResourcesFolderUtils.getResourcesFolderName(ResourcesFolderUtils.java:31)

at com.mathworks.mde.desk.ContributedTools.constructToolSetFileName(ContributedTools.java:103)

at com.mathworks.mde.desk.ContributedTools.<init>(ContributedTools.java:65)

at com.mathworks.mde.desk.ContributedToolsLoader$3.run(ContributedToolsLoader.java:69)

at java.lang.Thread.run(Thread.java:748)

Answer 1

[Monisha Nalluru]

The "NoClassDefFoundError" error is thrown because MATLAB was not able to locate Java Runtime libraries that are used by the Integrated Development Environment (MATLAB IDE).

There are several possible causes to this issue:

• The installation is corrupted and there are .jar files missing from the MATLAB installation folder
• The classpath.txt file is missing references to Java Runtime libraries
• One or several internal MATLAB functions are shadowed by custom functions

Try to restore the serach path to the installation default by excuting the following commands

restoredefaultpath
rehash toolboxcache
savepath

If the issue still persist, the installation might be corrupted. Remove MATLAB completely and install it again to resolve the issue

[Walter Roberson]

If I recall correctly, there have been cases where a corrupt preferences directory caused the problem.

In current releases, the Mac preferences directory appears to live at /Users/NAME/Library/Application Support/MathWorks/MATLAB/R2020b where NAME is your username