503 service unavilable

Hi, I have a cloud linux lightspeed web-server. One of the account show disk quota exceeded error message while trying to add a php.ini file through cpanel. But the account have enough space. Also while trying to access the domain it shows the "503 service unavailable error". I detected the logs as follows. ============================= tailf /usr/local/apache/logs/stderr.log Failed to start up concurrent users module! Sun Jun 30 18:26:01 2019 (32684): Fatal Error Unable to create lock file: Bad file descriptor (9) [29437] Child process with pid: 32670 was killed by signal: 15, core dump: 0 [33320] Child process with pid: 33325 was killed by signal: 15, core dump: 0 Unable to create lock file: Disk quota exceeded Failed to start up concurrent users module! Sun Jun 30 18:27:01 2019 (34125): Fatal Error Unable to create lock file: Bad file descriptor (9) Unable to create lock file: Disk quota exceeded Failed to start up concurrent users module! Sun Jun 30 18:28:01 2019 (35788): Fatal Error Unable to create lock file: Bad file descriptor (9) =============================== =============================== cat /usr/local/apache/logs/error_log | grep example.com 2019-06-30 10:19:09.350481 [INFO] [23.111.181.245:34829-1#APVH_example.com:lsapi] connection to [uds://tmp/lshttpd/APVH_example_Suea-php56.sock] on request #0, confirmed, 0, associated process: 0, running: 0, error: Connection reset by peer! 2019-06-30 10:19:09.350511 [NOTICE] [23.111.181.245:34829-1#APVH_example.com:lsapi] Max retries has been reached, 503! 2019-06-30 10:19:09.350973 [NOTICE] [23.111.181.245:34829-1#APVH_example.com:lsapi] oops! 503 Service Unavailable 2019-06-30 10:19:09.350983 [NOTICE] [23.111.181.245:34829-1#APVH_example.com:lsapi] Content len: 0, Request line: 'GET /index.php HTTP/1.1' 2019-06-30 10:19:09.351012 [INFO] [23.111.181.245:34829-1#APVH_example.com:lsapi] abort request..., code: 4 2019-06-30 10:19:09.351040 [INFO] [23.111.181.245:34829-1#APVH_example.com:lsapi] File not found [/home/example/public_html/503.shtml] 2019-06-30 12:56:35.239957 [INFO] [163.172.105.148:54873-1#APVH_example.com:lsapi] connection to [uds://tmp/lshttpd/APVH_example_Suea-php56.sock] on request #0, confirmed, 0, associated process: 0, running: 0, error: Connection reset by peer! 2019-06-30 12:56:35.240134 [INFO] [163.172.105.148:54873-1#APVH_example.com:lsapi] connection to [uds://tmp/lshttpd/APVH_example_Suea-php56.sock] on request #0, confirmed, 0, associated process: 0, running: 0, error: Connection refused! =============================== Let me know the possibility of this kind of error.