The message error "Your save has failed" shows like the below screenshot:
An error has occurred while saving your page. Various problems can cause a save to fail, such as a lack of server resources, firewall blockages, plugin conflicts or server misconfiguration. You can try saving again by clicking Try Again or download a backup of your unsaved page by clicking Download Backup. Backups can be restored using the portability system while editing your page.
Contacting your host and asking them to increase the following PHP variables may help: memory_limit, max_execution_time, upload_max_filesize, post_max_size, max_input_time, max_input_vars. In addition, auditing your firewall error log (such as ModSecurity) may reveal false positives preventing saves from completing.
Lastly, it is recommended that you temporarily disable all WordPress plugins and browser extensions and try to save again to determine if something is causing a conflict.
We should first know that this message is all about the saving process.
It could happen when you hit that save button, or the system saves the changes for you.
Possible cause #1 - Lack of Server Resources
The first suggested cause in the message is a lack of server resources. Make sure that the Server meets WordPress and Divi's requirements.
We can check that by going to Divi > Support Center > System Status and ensuring everything is in the Green.
If there are red dots, it indicates that a certain PHP directive doesn't meet the requirements. In this case, contacting the hosting support team and increasing the value should help.
Possible cause #2 - Firewall Blockages
The second suggested cause in the message is firewall blockages.
This issue is usually caused by the Server mod_security and it is usually seen on hosts that use cPanel or a cheaper shared host like Bluehost or GoDaddy.
This can happen when the hosting server misinterprets valid requests sent by Divi as malicious requests (false positives) and blocks them.
When this happens, opening the browser DevConsole (right-click on any page, choose "inspect", then select the Console tab) and inspecting the Console Tab will be a 403 - Access Forbidern error for the WordPress core file admin-ajax.php.
Solving this case will require contacting the hosting support team and letting them know about this type of error (403). They can check the Server's log file and whitelist the call that triggered that error.
Possible cause #3 - Security Plugin, Firewall Blockages
If the WordFence plugin is installed and active, we need to turn on a WordFence Learning Mode feature.
Go to WordPress Dashboard > WordFence > Firewall
Click on Manage WAF
Set the Web Application Firewall Status to Learning Mode:
Possible cause #4 Plugins/Custom Code/Child Theme Conflict
To ensure that none of the active plugins/child theme/custom code is the actual reason for the Saving process failing, enable Divi's Safe mode.
The Safe Mode can be enabled from WordPress Dashboard > Divi > Support Center.
With the Safe Mode enabled, try to edit and save the edits again.
If while the Safe mode is enabled, the Saving works as expected, we need to narrow down the cause.
Plugins
Go to WordPress Dashboard > Plugins
Deactivate all plugins
With all the plugins deactivated, check if the Saving process works
If deactivating plugins solves the issue
Go back to WordPress Dashboard > Plugins > Recently Active tab
Activate one plugin at a time
After each plugin activation, check if the Saving process works
Repeat steps 1, 2 and 3 until the issue happens again or all recently active plugins are activated.
If deactivating plugins doesn't solve the issue
In case of using a Child theme, deactivate it by activating the Parent Theme from WordPress Dashboard > Appearance > Themes
Deactivating any custom code (especially jQuery code)
Deactivate all sections in Divi > Theme Option > Integration tab.
Other possible causes and suggestions
Session Timed Out
The Saving process can fail when the session has timed out.
This sometimes happens when the Visual Builder is not closed when not actively working on the page, then the work is resumed.
At first glance, it lets us continue working just fine. However, the database session has already timed out and disconnected from the site, so whenever an attempt to save it will fail.
To avoid this, you can always exit the visual builder when you are not actively working.
WordPress Idle User Logout
WordPress has a default time when it logs out idle users for security reasons. It may vary depending on your setup or any plugins that modify it. You can adjust the automatic logout time with a plugin if needed.
Close Page, Open URL In New Tab
In some cases, closing the current browser tab and reopening the page URL again may solve the issue.
Emojis
Try not to use Emojis in any modules. The presence of a single Emoji inside a module's content will prevent the Saving from completing, showing the Save Has failed message.
Code Module
If a Code module is being used in the page layout, ensure that the content (HTML/CSS/JS codes) is correct and does not have any syntax problems.
Sometimes, unclosed HTML tags can have unwanted results.
Avoid Editing From Frontend And Backend Simultaneously
Avoid having the same page opened in both the backend Editor and the Visual Builder. Opening the same page in both editors can sometimes prevent the Saving process from completing.