Hi @seyedahmadqz,
Can you please ensure you are using the latest version of all of your extensions? You can find if you have any out-of-date by going to the WooCommerce → Status report.
This is likely caused by a conflict with your theme or with another plugin. Read more about plugin and theme conflicts in our [Self-Service Guide](https://docs.woocommerce.com/document/woocommerce-self-service-guide/).
How to test for conflicts
The best way to determine if the issue is being caused by a theme and/or plugin is to:
1. Temporarily switch your theme to the Storefront (https://woocommerce.com/products/storefront/) or TwentySeventeen (https://wordpress.org/themes/twentyseventeen/) theme.
2. Try to reproduce the problem. If it is resolved, you have a theme conflict. If not, continue to the next step.
3. Temporarily deactivate all plugins except WooCommerce. You can do this manually or use a plugin to help (see below for tools).
4. Try to reproduce the problem again. If the problem is resolved, it is a plugin conflict. To figure out which plugin is causing the problem, continue to the next step.
5. Reactivate your other plugins one by one, testing after each, until you find the one causing conflict
For more detailed instructions, check out How to test for plugin and theme conflicts (https://docs.woocommerce.com/document/how-to-test-for-conflicts/).
Please let us know how that goes.
**Tools to help with troubleshooting**
Meks Quick Plugin Disabler (https://wordpress.org/plugins/meks-quick-plugin-disabler/) will remember what plugins you had active when you switch it back on.
Health Check (https://wordpress.org/plugins/health-check/) can be useful for debugging certain types of issues and requires an official default WordPress theme such as Twenty Seventeen (https://wordpress.org/themes/twentyseventeen/). See Troubleshooting using Health Check (https://docs.woocommerce.com/document/troubleshooting-using-health-check/) for more details.
You can clone your site to a staging environment and perform tests without modifying your live site or impacting customers. Many hosts provide staging facilities, so it’s worth checking in with them. It’s also possible to do it using the free WP Staging (https://wordpress.org/plugins/wp-staging/) plugin.
All the best,
