PHPUnit undefined method call

I've run into a puzzling error when I try to run my global PHPUnit in a project.

My system-wide PHPUnit is version 7.2.6 and my PHP version is 7.2.7.

Here is the error that I get:

PHPUnit 7.2.6 by Sebastian Bergmann and contributors.
PHP Fatal error:  Uncaught Error: Call to undefined method PHPUnit\Util\Configuration::hasValidationErrors() in /Users/ronald/Sites/painting/vendor/phpunit/phpunit/src/TextUI/TestRunner.php:337
Stack trace:
#0 /Users/ronald/.composer/vendor/phpunit/phpunit/src/TextUI/Command.php(198): PHPUnit\TextUI\TestRunner->doRun(Object(PHPUnit\Framework\TestSuite), Array, true)
#1 /Users/ronald/.composer/vendor/phpunit/phpunit/src/TextUI/Command.php(151): PHPUnit\TextUI\Command->run(Array, true)
#2 /Users/ronald/.composer/vendor/phpunit/phpunit/phpunit(53): PHPUnit\TextUI\Command::main()
#3 {main}
  thrown in /Users/ronald/Sites/painting/vendor/phpunit/phpunit/src/TextUI/TestRunner.php on line 337

Fatal error: Uncaught Error: Call to undefined method PHPUnit\Util\Configuration::hasValidationErrors() in /Users/ronald/Sites/painting/vendor/phpunit/phpunit/src/TextUI/TestRunner.php on line 337

Error: Call to undefined method PHPUnit\Util\Configuration::hasValidationErrors() in /Users/ronald/Sites/painting/vendor/phpunit/phpunit/src/TextUI/TestRunner.php on line 337

Call Stack:
    0.0026     395856   1. {main}() /Users/ronald/.composer/vendor/phpunit/phpunit/phpunit:0
    0.0512    1935008   2. PHPUnit\TextUI\Command::main() /Users/ronald/.composer/vendor/phpunit/phpunit/phpunit:53
    0.0512    1935120   3. PHPUnit\TextUI\Command->run() /Users/ronald/.composer/vendor/phpunit/phpunit/src/TextUI/Command.php:151
    0.0960    5578520   4. PHPUnit\TextUI\TestRunner->doRun() /Users/ronald/.composer/vendor/phpunit/phpunit/src/TextUI/Command.php:198

The funny thing is that it works when I run vendor/bin/phpunit but not the global PHPUnit. I can run the global version in any of my projects and it works just fine, so I'm not sure what the problem is.

Lastly, here is my phpunit.xml file.

<?xml version="1.0" encoding="UTF-8"?>
<phpunit backupGlobals="false"
         backupStaticAttributes="false"
         bootstrap="vendor/autoload.php"
         colors="true"
         convertErrorsToExceptions="true"
         convertNoticesToExceptions="true"
         convertWarningsToExceptions="true"
         processIsolation="false"
         stopOnFailure="false">
    <testsuites>
        <testsuite name="Feature">
            <directory suffix="Test.php">./tests/Feature</directory>
        </testsuite>

        <testsuite name="Unit">
            <directory suffix="Test.php">./tests/Unit</directory>
        </testsuite>
    </testsuites>
    <filter>
        <whitelist processUncoveredFilesFromWhitelist="true">
            <directory suffix=".php">./app</directory>
        </whitelist>
    </filter>
    <php>
        <env name="APP_ENV" value="testing"/>
        <env name="CACHE_DRIVER" value="array"/>
        <env name="SESSION_DRIVER" value="array"/>
        <env name="QUEUE_DRIVER" value="sync"/>
        <env name="MAIL_DRIVER" value="array"/>
        <env name="DB_CONNECTION" value="sqlite_testing" />
    </php>
</phpunit>