PHP Job Website Bug Fixing(English)

Hi, I have one website using php to develop. The website is lowongan job posting website, but my website has many problem and i want to fix these problem. There are some page become 505 error, I don't know why. So I need someone can develop and analyze to fix problem that cannot access to job page. If you can speak english and you can use php well, please let me know.

PHP

Published Budget: Rp 500,000 - 1,000,000
Finish Days: 7
Published Date: 02/12/2020 17:45:36 WIB
Start Date: 03/12/2020 07:26:54 WIB
Finish Date: 23/02/2021 16:30:30 WIB

Project Status: Closed
Accepted Worker: Rival M (jemz_08)
Accepted Budget: Rp 600,000
Project Ending: Arbitrated

Project Owner

mitachan
Kota Denpasar

9.48/10.00
1,310 Point
#462 dari 1,293,743

Accepted Worker

jemz_08
Kab. Bandung Barat

10.00/10.00
165 Point
#2,877 dari 1,293,743

Penyelesaian Arbitrase

Tim Arbitrator sudah memberikan keputusan berdasarkan fakta-fakta yang tercatat di sistem kami. Adapun keputusan yang diambil adalah sebagai berikut:

0%
dari dana project atau sebesar Rp 0 untuk Owner mitachan.
100%
dari dana project atau sebesar Rp 600,000 untuk Worker jemz_08 (belum dipotong fee, jika ada).

Di samping itu Tim Arbitrator juga memberikan rating kepada kedua belah pihak sebagai berikut: