Harness exports "javatestClassDir" environment variable that usually contains absolute path to the "javatest.jar". If the actual path name has white spaces inside (or other special characters), then the exported value will be mistakenly encoded.

For example:
(1) "tck dir with spaces/lib/javatest.jar"
=>
(2) "tck%20dir%20with%20spaces/lib/javatest.jar"

Since the encoded file name (2) cannot be resolved, the "javatestClassDir" variable will point to the non-existing directory that causes TCK tests to fail.