---
title: "Commonly found issues"
description: "Answers to common J2Commerce questions, including the warning shown when you install a new version over an existing one."
url: "https://docs.j2commerce.com/frequently-asked-questions/commonly-found-issues"
markdown_url: "https://docs.j2commerce.com/frequently-asked-questions/commonly-found-issues.md"
last_updated: "2026-10-23T03:36:49+00:00"
version: "J2Store 4"
breadcrumbs:
  - title: "Home"
    url: "https://docs.j2commerce.com/"
  - title: "Frequently Asked Questions"
    url: "https://docs.j2commerce.com/frequently-asked-questions"
  - title: "Commonly found issues"
    url: "https://docs.j2commerce.com/frequently-asked-questions/commonly-found-issues"
---

# Commonly found issues

## On update to 3.3.6

[Starting from the release 3.3.6, when you install the latest version of J2Commerce on your site over an existing version, you might find a warning that looks like this: ![PHP error](https://docs.j2commerce.com/images/docs/v4/doc-images/frequently-asked-questions/commonly-found-issues/error-j2store-exists.png) **Why does it occur?** This is just a warning. This warning indicates that there is already an existing version of J2Store available on the site, and now a new version has been installed over an existing version. **Will this harm my site?** No, this warning wouldn’t affect the site in any way. As mentioned before, this is just a warning, and you could ignore this.](https://docs.j2commerce.com/frequently-asked-questions/commonly-found-issues#on-update-to-336)

## [Due to the backward compatibility to earlier versions of PHP](https://docs.j2commerce.com/frequently-asked-questions/commonly-found-issues#on-update-to-336)

[Sometimes, you could find a warning like this on your site: ![PHP backward compatibility](https://docs.j2commerce.com/images/docs/v4/doc-images/frequently-asked-questions/commonly-found-issues/warning-php.png) **Why does it occur?** This warning occurs when you turn on Error reporting on your site’s global configuration under System > Global configuration > Server tab. This occurs since we provide backward compatibility to the earlier versions of PHP. **Will this harm my site?** No, this wouldn’t harm your site in any way. To overcome this, you could turn off the error reporting under Joomla! global configuration.\*\* **Why does it occur?** This warning occurs when you turn on Error reporting on your site’s global configuration under System > Global configuration > Server tab. This occurs since we provide backward compatibility to the earlier versions of PHP. **Will this harm my site?** No, this wouldn’t harm your site in any way. To overcome this, you could turn off the error reporting under Joomla! global configuration.\*\*](https://docs.j2commerce.com/frequently-asked-questions/commonly-found-issues#due-to-the-backward-compatibility-to-earlier-versions-of-php)

## [Issue:](https://docs.j2commerce.com/frequently-asked-questions/commonly-found-issues#due-to-the-backward-compatibility-to-earlier-versions-of-php)

[**Unable to save anything on the site** This might be because of two prominent reasons. **Database Type** or **Caching** **Check Database Type** Go to System > Global configuration ![Joomla System Dashboard with System in the sidebar and the Setup > Global Configuration link highlighted](https://docs.j2commerce.com/images/docs/shared/global-config.webp) Server tab ![Database-type](https://docs.j2commerce.com/images/docs/shared/global-config1.webp) **Database Type:** Should be set to **MySQLi** **Check Caching:** This issue might also be because of caching. Try clearing the cache and disabling the site, browser, and server-side caching, if any, and then try saving the settings.](https://docs.j2commerce.com/frequently-asked-questions/commonly-found-issues#issue)