Deleting or importing extensions in ThingWorx returns error "Cannot clean UI registration file [<tomcat_home>\webapps\Thingworx\Builder\index.html]"

• Installing or removing extensions from ThingWorx fails with below error:

Unable to execute service DeleteExtensionPackage on PlatformSubsystem: An error occurred while registering JavaScript resources. Check application log for more details

• <tomcat_home>\webapps\Thingworx\Builder\index.html missing
• Extensions from the PTC software download page are failing to import with error in \ThingworxStorage\logs\ErrorLog.log:

[L: ERROR] [O: E.c.q.l.c.Logger] [I: ] [U: SuperUser] [S: ] [P: ] [T: https-jsse-nio-443-exec-9] Error occurred updating the resource registration files. 
[L: ERROR] [O: E.c.q.l.c.Logger] [I: ] [U: SuperUser] [S: ] [P: ] [T: https-jsse-nio-443-exec-9] Cannot clean UI registration file [<tomcat_home>\webapps\Thingworx\Builder\index.html] because it does not exist 
[L: ERROR] [O: E.c.q.l.c.Logger] [I: ] [U: SuperUser] [S: ] [P: ] [T: https-jsse-nio-443-exec-9] Error occurred cleaning the resource registration files. 

• Installed extensions fail to delete with error in \ThingworxStorage\logs\ErrorLog.log:
  
  

[L: ERROR] [O: E.c.q.l.c.Logger] [I: ] [U: SuperUser] [S: ] [P: ] [T: https-jsse-nio-443-exec-9] Error occurred updating the resource registration files. 
[L: ERROR] [O: E.c.q.l.c.Logger] [I: ] [U: SuperUser] [S: ] [P: ] [T: https-jsse-nio-443-exec-9] Cannot clean UI registration file [<tomcat_home>\webapps\Thingworx\Builder\index.html] because it does not exist 
[L: ERROR] [O: E.c.q.l.c.Logger] [I: ] [U: SuperUser] [S: ] [P: ] [T: https-jsse-nio-443-exec-9] Error occurred cleaning the resource registration files. 
[L: ERROR] [O: E.c.q.l.c.Logger] [I: ] [U: SuperUser] [S: ] [P: ] [T: https-jsse-nio-443-exec-9] ERROR - un-installing Extension Package: <extension>_ExtensionPackage 
[L: ERROR] [O: E.c.q.l.c.Logger] [I: ] [U: SuperUser] [S: ] [P: ] [T: https-jsse-nio-443-exec-9] Unable to delete <extension>_ExtensionPackage:2.0.0.  This is likely due to other errors: An error occurred while registering JavaScript resources. Check application log for more details. 

• Below errors appear in \ThingworxStorage\logs\ErrorLog.log:
  

An error occurred while registering JavaScript resources. Check application log for more details. java.nio.file.AccessDeniedException: ####\webapps\Thingworx\Builder\index.html at java.base/sun.nio.fs.WindowsException.translateToIOException(WindowsException.java:89)
       at java.base/sun.nio.fs.WindowsException.rethrowAsIOException(WindowsException.java:103)
       at java.base/sun.nio.fs.WindowsException.rethrowAsIOException(WindowsException.java:108)
       at java.base/sun.nio.fs.WindowsFileCopy.copy(WindowsFileCopy.java:164)
       at java.base/sun.nio.fs.WindowsFileSystemProvider.copy(WindowsFileSystemProvider.java:283)
       at java.base/java.nio.file.Files.copy(Files.java:1295)