Why OpenCart 4?

OpenCart 4 brings PHP 8 performance/security, a refreshed admin, and architectural changes around extensions/events, making it attractive for new builds on modern stacks, while 3.x remains a proven path for shops with complex themes and modules that may not yet be 4.x‑ready. For production, the decision usually depends on extension/theme compatibility and team comfort with PHP 8.2+ hosting.

Part 1: Prerequisites and hosting

System requirements: Ensure the server meets OpenCart requirements (Apache/Nginx, MySQL/MariaDB, PHP 8.x); verify file permissions for installation and runtime.

PHP version guidance: OpenCart 4 requires PHP 8.0+ and is commonly deployed on PHP 8.1/8.2; older 3.0.x maintenance supports PHP 8.x as an alternative if 4.x compatibility is a concern.

Part 2: Download and file upload

Obtain OpenCart 4: Download the latest OpenCart package from the official site and upload the contents of the “upload” directory to the web root via SFTP/FTP.

Prepare database: Create a MySQL/MariaDB database and user with proper privileges before running the installer; note DB host, user, password, and name.

Part 3: Run the web installer

Start installer: Visit the domain to trigger the installer, accept license, and confirm requirement checks go green; fix permissions if any checks fail.

Configure DB and admin: Enter database credentials, then set admin username, strong password, and email; complete and sign in to the admin panel after installation.

Suggested screenshots:

OpenCart installer “Requirements” step.

The form where database/admin credentials are entered.

Part 4: Initial store configuration

Store identity and localization: In Admin → System → Settings → Edit Store, set Store Name, Owner, Address, Email, and switch to Local tab to set Country, Zone, Language, Currency, Length and Weight classes.

Why localization matters: Accurate locale settings drive tax/shipping calculations and payment gateway behavior, so complete these before products go live.

The General tab with basic store identity filled.

Part 5: Languages

Add languages: Go to Admin → System → Localisation → Languages to add additional languages, then enable and set default as needed; translate content via Language Editor or direct language packs.

Content strategy: Multilingual stores should plan SEO slugs, hreflang usage, and per‑language category/product texts early for consistency and search visibility.

Add Language form with code/locale details.

Part 6: Currencies

Add and set default currency: Admin → System → Localisation → Currencies → Insert to add codes and symbols, then set default in System → Settings → Local tab; enable auto‑update if desired.

Multi‑currency UX: Provide a visible currency switcher and confirm rounding/format in product/card, cart, and checkout flows.

Part 7: Taxes and rates

Tax basics: Configure geo zones, tax classes, and rates matching the store’s operational country to ensure correct tax at checkout; align with Local settings from earlier.

Step order: Set Country/Zone, define Geo Zones, create Tax Classes (e.g., Standard Rate), then assign Tax Rates by Geo Zone and Customer Group as applicable.

Part 8: Core features to leverage early

Admin improvements and extension approach: OpenCart 4 modernizes admin and emphasizes events over legacy OCMOD, with extensions organized under /extension/ by vendor/type to reduce collisions and improve maintainability.

PHP 8 benefits: Faster execution and stricter typing can surface issues early, but yields performance/security wins once the stack is configured and codepaths are 8.x‑clean.

Part 9: Migration plan from OpenCart 3.x to 4.x

When to migrate: New builds or sites with minimal third‑party complexity benefit most from 4.x; heavy 3.x ecosystems may stay on maintained 3.0.x for stability until all critical modules/themes are 4‑ready.

Compatibility checks: Audit every extension and theme in 3.x for 4.x availability; confirm PHP 8 readiness; identify replacements if developers have not updated; note that extension architecture differs in 4.x.

Part 10: Extension/theme audit steps

Extension inventory: Export a list of all OCMODs, events, vQmods (if present), and installed modules; remove unused ones to reduce risk surface pre‑migration.

Theme strategy: If the theme isn’t 4‑ready, consider a default theme start and re‑apply branding incrementally; this avoids blockers and reduces conflicts during upgrade.

Part 11: Staging, backup, and rollback

Staging first: Clone the site/database into a staging subdomain; upgrade there and test flows, then schedule a maintenance window for production if green.

Backups: Full file and DB backup; keep copies of config.php and admin/config.php safely; verify recovery by restoring on a local or alternate sandbox before final cutover.

Part 12: Data migration and install steps

Clean install approach: For many, the safest route is a fresh OC 4 install, then migrate data (customers, orders, products, categories, settings) using export/import tools or scripted ETL, then re‑install 4.x compatible extensions.

Direct replace approach: Upload OC 4 files carefully, do not overwrite config.php files, and run necessary upgrade scripts—but this path needs extra caution due to architectural changes.

Part 13: Test plan before go‑live

Functional smoke tests: Product browse, search, cart, checkout (guest + logged‑in), payment sandbox, taxes/shipping, emails, admin order management, and refunds.

Edge checks: Multilingual URLs, multi‑currency rounding, tax exemptions, coupon usage, and performance on category pages; log and resolve any PHP 8 warnings/notices surfaced.

Part 14: Performance and SEO touch‑ups

Quick wins: Enable caching/CDN, WebP images, and database tuning; validate canonical URLs and structured data if using SEO extensions; fix any 404s from changed routes/templates.

Modern front‑end: OC 4 adopts updated Bootstrap and jQuery, so verify custom JS/CSS for deprecations and ship a minified bundle; re‑check Core Web Vitals post‑launch.

Part 15: Ready‑to‑upgrade checklist

Must‑have green lights: Full backups, staging passed, all critical extensions/themes 4.x compatible, PHP 8.2/8.3 runtime validated, tax/currency/language configured, payment sandboxed cleanly, rollback tested.

Timing and comms: Pick a low‑traffic window, put site in maintenance mode, cut over, run post‑deploy checks, and monitor error logs/analytics for 24–48 hours to catch regressions early.

Above all why not????

BUGS!

WebiggleStore wrote: ↑

Sat Sep 06, 2025 4:18 am

OpenCart 4 brings PHP 8 performance/security, a refreshed admin, and architectural changes around extensions/events, ..and so on ...

Okay, to say the truth: currenly it IS NOT RECOMMENDED to use OpenCart 4.x version for live shops!
Why?
Ongoing daily development, not stable, too many bugs.

(Don't know why you are writing this post, if you want to advertise your services, there are better ways to do .. otherwise a forum ban could be follow).