http error 500

i have installed projeqtor on ubuntu server, but it cannot login ( http error 500). when i checked apache error i get the following result:



[Wed Dec 20 15:05:28.768653 2017] [:error] [pid 21814] [client 10.20.30.61:51929] PHP Fatal error: Uncaught Error: Class 'Parameter' not found in /var/www/html/projeqtor/tool/projeqtor.php:557\nStack trace:\n#0 [internal function]: exceptionHandler(Object(ParseError))\n#1 {main}\n thrown in /var/www/html/projeqtor/tool/projeqtor.php on line 557
[Wed Dec 20 15:05:28.910855 2017] [:error] [pid 21817] [client 10.20.30.61:51930] PHP Fatal error: Uncaught Error: Class 'Parameter' not found in /var/www/html/projeqtor/tool/projeqtor.php:557\nStack trace:\n#0 [internal function]: exceptionHandler(Object(ParseError))\n#1 {main}\n thrown in /var/www/html/projeqtor/tool/projeqtor.php on line 557
[Wed Dec 20 15:05:29.450907 2017] [:error] [pid 21815] [client 10.20.30.61:51931] PHP Fatal error: Uncaught Error: Class 'Parameter' not found in /var/www/html/projeqtor/tool/projeqtor.php:557\nStack trace:\n#0 [internal function]: exceptionHandler(Object(ParseError))\n#1 {main}\n thrown in /var/www/html/projeqtor/tool/projeqtor.php on line 557
[Wed Dec 20 15:05:29.628544 2017] [:error] [pid 21816] [client 10.20.30.61:51932] PHP Fatal error: Uncaught Error: Class 'Parameter' not found in /var/www/html/projeqtor/tool/projeqtor.php:557\nStack trace:\n#0 [internal function]: exceptionHandler(Object(ParseError))\n#1 {main}\n thrown in /var/www/html/projeqtor/tool/projeqtor.php on line 557
[Wed Dec 20 15:05:29.781203 2017] [:error] [pid 21813] [client 10.20.30.61:51933] PHP Fatal error: Uncaught Error: Class 'Parameter' not found in /var/www/html/projeqtor/tool/projeqtor.php:557\nStack trace:\n#0 [internal function]: exceptionHandler(Object(ParseError))\n#1 {main}\n thrown in /var/www/html/projeqtor/tool/projeqtor.php on line 557
[Wed Dec 20 15:07:59.011268 2017] [mpm_prefork:notice] [pid 21810] AH00169: caught SIGTERM, shutting down
[Wed Dec 20 15:08:00.100126 2017] [mpm_prefork:notice] [pid 21903] AH00163: Apache/2.4.18 (Ubuntu) configured -- resuming normal operations
[Wed Dec 20 15:08:00.100188 2017] [core:notice] [pid 21903] AH00094: Command line: '/usr/sbin/apache2'
[Wed Dec 20 15:08:05.260421 2017] [:error] [pid 21908] [client 10.20.30.61:52034] PHP Fatal error: Uncaught Error: Class 'Parameter' not found in /var/www/html/projeqtor/tool/projeqtor.php:557\nStack trace:\n#0 [internal function]: exceptionHandler(Object(ParseError))\n#1 {main}\n thrown in /var/www/html/projeqtor/tool/projeqtor.php on line 557
[Wed Dec 20 15:08:07.308888 2017] [:error] [pid 21907] [client 10.20.30.61:52035] PHP Fatal error: Uncaught Error: Class 'Parameter' not found in /var/www/html/projeqtor/tool/projeqtor.php:557\nStack trace:\n#0 [internal function]: exceptionHandler(Object(ParseError))\n#1 {main}\n thrown in /var/www/html/projeqtor/tool/projeqtor.php on line 557