Expert OpenCart Multi-Store Developer Needed – Fix PHP/MySQL Errors, Performance, Security & Log Issues
Summary
Freelancer Client is hiring: Expert OpenCart Multi-Store Developer Needed – Fix PHP/MySQL Errors, Performance, Security & Log Issues.
Location: Remote
We are looking for a highly experienced OpenCart / PHP / MySQL developer to audit, repair and optimise a heavily customised OpenCart multi-store online ordering platform.
Requirements:
• Please only apply if you have strong experience with:
• OpenCart, ideally OpenCart 1.5.x / older customised OpenCart systems
• OpenCart multi-store architecture
• MySQL / MariaDB optimisation
• custom payment modules
• custom checkout systems
• debugging production websites
• SQL injection prevention
Nice to have:
• We are looking for a senior developer, not someone who only installs OpenCart extensions. The right person should be able to understand an old customised system, trace issues properly, and fix them without breaking live ordering.
Skills: PHP, Linux, Web Security, MySQL, Debugging, cPanel
Budget: $250–$750 USD
Source: Freelancer Client via Remote / Online. Apply on the source website.
Original
We are looking for a highly experienced OpenCart / PHP / MySQL developer to audit, repair and optimise a heavily customised OpenCart multi-store online ordering platform.
This is not a standard OpenCart installation. It is a customised multi-store takeaway/restaurant ordering system with custom payment modules, SMS integrations, printer settings, VQMod modifications, custom checkout, and multiple store configurations.
We need someone who can investigate and fix recurring errors, improve performance, clean up old/unused code, and make the platform stable and secure.
Main Issues to Fix
The site currently has several serious problems that need professional investigation and permanent fixes:
1. PHP Error Log Growing to GB Size
The error log is constantly growing because repeated PHP Notice/Warning messages are being written on every page load.
Examples include:
Undefined variable: uniqueDates
array_filter() expects parameter 1 to be array, null given
array_map(): Expected parameter 2 to be an array, null given
array_search() expects parameter 2 to be array, null given
Undefined variable: openingDayTime
Undefined index: flagpostcode
These appear mainly around:
catalog/controller/common/header.php
catalog/controller/module/minicart.php
vqmod/vqcache/vq2-catalogcontrollercommon_header.php
The selected developer must fix the source files properly, not just hide warnings.
2. MySQL Connection and Server Stability Problems
We have seen recurring database errors such as:
Too many connections
Could not make a database link
MySQL server has gone away
Allowed memory size exhausted
The developer must investigate whether this is caused by bad queries, connection leaks, cron jobs, bot traffic, missing indexes, bad configuration, or inefficient code.
3. PHP Memory Exhaustion
There are repeated fatal errors such as:
Allowed memory size of 268435456 bytes exhausted
These appear in files such as:
catalog/model/setting/setting.php
system/database/mysqli.php
vqmod/vqcache/vq2-systemengineloader.php
vqmod/vqcache/vq2-catalogcontrollercommon_header.php
We need the root cause fixed, not just increasing PHP memory limit.
4. OpenCart Multi-Store Setting Problems
The system appears to delete and reinsert oc_setting values when saving store settings.
This may cause temporary missing settings such as:
config_template
config_url
config_ssl
config_name
We have also seen errors like:
Failed opening required '/home/myfoodbasket/public_html/catalog/view/theme/'
This suggests some stores may temporarily or permanently have missing/empty theme configuration.
The developer must check the store settings save logic and ensure settings are updated safely.
5. Query Debug Logs Exposing Sensitive Data
There are query log files that record full SQL queries, including sensitive configuration values such as:
SMS API URLs
API keys
printer usernames/passwords
payment gateway settings
store configuration details
This logging must be disabled or replaced with safe masked logging. Old sensitive logs must be identified and removed or moved outside public access.
6. Product Stock Updates Running Even Though We Do Not Use Stock
We do not use product stock for our takeaway/restaurant products, but the system is still running queries like:
UPDATE oc_product SET quantity = (quantity - 1)
WHERE product_id = '...' AND subtract = '1'
These are called from payment modules such as:
catalog/controller/payment/acquiredcom.php
catalog/controller/payment/cod.php
catalog/controller/payment/worldpayhp.php
The developer must disable unnecessary stock deduction logic safely and make sure it does not affect order flow.
7. Security Review
Logs show suspicious SQL payload attempts around product/topping parameters, including SQL injection style strings.
The developer must review vulnerable areas, especially custom topping/option/product functions, and ensure all inputs are validated and safely cast or escaped.
Required checks include:
SQL injection protection
request parameter validation
session data validation
payment callback safety
admin-side sensitive logging
public access to log files
old/unused files or broken endpoints
8. Clean Up Unused or Broken Links / Code
We also want the developer to review and clean up:
unused external scripts/CSS
broken links
obsolete API integrations
old payment/SMS/debug code
unused modules
duplicate or unnecessary JS/CSS includes
VQMod cache/source mismatch issues
unnecessary database queries
9. Performance Optimisation
The site must be optimised for speed and stability.
We expect the developer to review:
slow queries
missing indexes
excessive queries per page
unnecessary config loading
VQMod overhead
cache usage
database connection handling
PHP warnings/notices
log rotation
cron job impact
bot traffic impact
checkout and basket performance
Required Skills
Please only apply if you have strong experience with:
OpenCart, ideally OpenCart 1.5.x / older customised OpenCart systems
OpenCart multi-store architecture
PHP 7.x
MySQL / MariaDB optimisation
VQMod
custom payment modules
custom checkout systems
debugging production websites
SQL injection prevention
server performance optimisation
Linux/cPanel hosting environments
error log analysis
Deliverables
The successful freelancer must provide:
Full audit of current issues.
Clear list of all problems found.
Permanent fixes for PHP notices/warnings/fatal errors.
Fixes for MySQL connection and performance problems.
Secure handling of logs and sensitive data.
Removal or disabling of unnecessary stock deduction logic.
Cleanup of unused/broken code and links.
Performance improvements for frontend and checkout.
Before/after summary.
List of files changed.
SQL changes made, if any.
Recommendations for future maintenance.
Important Requirements
Do not apply generic OpenCart fixes without understanding the custom system.
Do not simply suppress errors; root causes must be fixed.
Do not modify live payment/order flow without taking backups and explaining the change.
Must be able to work carefully on a production multi-store ordering platform.
Must communicate clearly and explain what was changed.
Must be available for testing after fixes.
Questions for Applicants
Please answer these when applying:
Have you worked with customised OpenCart multi-store systems before?
Have you worked with OpenCart 1.5.x or older OpenCart versions?
Can you debug VQMod-generated errors back to the original source files?
How would you investigate Too many connections and MySQL server has gone away errors?
How would you safely disable stock deduction in a custom ordering system?
Can you review logs without exposing sensitive API/payment credentials?
Are you comfortable working with custom payment modules and checkout logic?
Preferred Type of Freelancer
We are looking for a senior developer, not someone who only installs OpenCart extensions. The right person should be able to understand an old customised system, trace issues properly, and fix them without breaking live ordering.
Location & Details
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