Build Stuck at 5% or Pending

The build process can get stuck at 5% or show as pending due to various issues, mostly related to AJAX communication failures.

Follow these steps sequentially to resolve the issue:

Option 1 – Check Admin-AJAX Protocol

Mismatch in Protocols: If your wp-admin URL uses HTTPS instead of HTTP, changing the AJAX protocol might solve the issue.

Steps:

1. Go to Settings » Backups » Advanced Settings.
2. Change the AJAX setting to HTTPS.
3. Save settings and retry the build.

Option 2 – Host Blocking Localhost Traffic

Localhost Blocking: Some hosting environments prevent the server from calling back to itself, often due to services like Fail2Ban.

Steps:

1. Go to Settings » Backups » Advanced Settings.
2. Set Client-Side Kickoff to Auto. This is a three-way option (Disabled, Enabled, Auto) and Auto is the recommended setting.
3. Save settings and retry the build.

Note: If Duplicator shows a notice after saving that Client-Side Kickoff is active, we recommend setting up a remote cron job so scheduled builds don’t depend on site traffic to trigger. See Ensure Your Scheduled Build Runs On Time.

Option 3 – Basic Authentication Issue

Basic Authentication: Basic authentication is likely enabled if accessing wp-admin requires entering credentials in a popup login window.

Steps:

1. Go to Settings » Backups » Advanced Settings.
2. Set Basic Auth to your credentials under Password-Protected Access.
3. Save settings and retry the build.

Option 4 – Security Plugin Blocking Admin-AJAX

Security Plugins: Security plugins might block AJAX requests needed for the build process.

Steps:

1. Disable any security plugins.
2. Run a backup build.
3. If the build works, re-enable plugins individually to isolate the problematic setting.

Option 5 – Host Blocking Admin-AJAX

Host-Level Block: Some hosting providers have rules in place that block calls to admin-ajax.php. In this case, please reach out to your hosting provider.

Pending State

A backup in the pending state often indicates that a backup created by a schedule can’t be processed due to an AJAX communication failure.

Steps:

1. Manually build a backup (instead of using a schedule).
2. If that backup gets stuck at 5%, see Options 1-5 for details on how to resolve it.

Build Stuck around 20%

Sticking at the 20% mark generally points to problems associated with capturing the database.

Switch Database Script Engine

Switch Database Setting:
Change the database setting from PHP Code to Mysqldump or vice versa.

Steps:
Go to Settings » Backups and change the Database setting.

Optimize Tables

Consider optimizing your database with a plugin like wp-sweep or similar to remove unnecessary data.

Steps:

1. Optimize your tables using the wp-sweep plugin.
2. Look for and remove tables that won’t be useful after migration (e.g., logs).

Build Stuck around 40%

Low-resource hosts might kill the zip process due to constraints, causing the build process to restart at 40%.

Switch to DupArchive (Recommended First)

If a low-resource host is killing the zip process, switching to the DupArchive engine is usually the most effective fix, since it avoids the memory/CPU spikes that trigger this specific kill. Go to Settings » Backups » Archive Engine and select DupArchive.

Filtering Files

If switching engines doesn’t resolve it, filter out larger files/directories to identify if the issue is site size related. Use the file/directory filter option in both Shell mode and ZipArchive mode.
Adjust Max Build Time

If the build is being auto-cancelled rather than killed by the host, check Settings » Backups and raise the Max Build Time value (measured in minutes), the default is 270 minutes, and 0 removes the limit entirely.

Switch to ZipArchive

If you’re currently on Shell Zip, switching to the older ZipArchive engine could also resolve the issue.

If you’re migrating a large site on a budget host in general, see Tips for migrating a large website on a limited hosting plan. For more on working with DupArchive/.daf files directly, see Extracting .daf file with DupArchive Extractor.

Make sure to follow these steps in a sequential manner, and you should be able to resolve the issues with builds getting stuck at a particular percentage point.