Fix “PCLZIP_ERR_BAD_FORMAT (-10): Unable to find End of Central Dir Record signature” in UpdraftPlus

If you’re wondering what’s actually broken: it’s almost never the UpdraftPlus code. It’s the backup ZIP file WordPress is trying to open.

Why this error shows up in UpdraftPlus

UpdraftPlus uses WordPress’s built in ZIP library (PclZip) to unpack your backup archives.

This error:

PCLZIP_ERR_BAD_FORMAT (-10): Unable to find End of Central Dir Record signature

means PclZip could not find the “end of central directory” marker inside the file. In plain terms, WordPress sees the file as:

• Corrupted, or
• Incomplete (truncated during backup, download, or upload), or
• Blocked by a storage or filesystem issue while being unpacked.

The good news: if you still have a clean copy of that backup in remote storage or on another machine, you can usually recover.

Step 1: Confirm which backup file is broken

First, you want to know exactly which archive is failing: database, plugins, themes, uploads, or others.

Do this:

1. In WordPress, go to Settings → UpdraftPlus Backups.
2. On the Existing Backups tab, find the backup you are trying to restore.
3. Click View Log or download the log file for that restore attempt.
4. Search the log for PCLZIP_ERR_BAD_FORMAT or End of Central Dir Record signature.

You should see a line that points at a specific file, for example:

• plugins.zip
• themes.zip
• uploads.zip or something similar

Make a note of which archive is mentioned and its size on disk in wp-content/updraft.

Step 2: Test the archive on your computer

Now you want to know whether the backup file itself is broken, or if the problem only shows up on the server.

Do this:

1. From the Existing Backups list, download the failing component (for example, the uploads ZIP) to your computer.
2. Try to open it locally using your operating system’s ZIP utility:
   • On Windows, right click → Extract All.
   • On macOS, double click it to extract.
   • On Linux, use your file manager or unzip from the command line.

Now compare what happens with these two cases:

Case A: Your computer also says the zip is invalid or can’t be opened.
This almost always means the backup archive is actually corrupted or incomplete. UpdraftPlus can’t fix that file; you will need a clean copy. Skip ahead to Get a clean copy of the backup.

Case B: Your computer opens the zip and shows the files normally.
That means the archive is likely fine, and the issue is how the server is handling it (disk space, permissions, or timeouts). Skip to Server side checks.

Step 3: Get a clean copy of the backup (if the zip is corrupted)

If the archive will not open on your computer, treat it as damaged. At this point, the fix is about finding another copy, not “repairing” this one.

If your backups are stored remotely (Drive, Dropbox, S3, UpdraftVault, etc.)

1. Log in to your remote storage (for example Google Drive or Dropbox).
2. Download the same backup component directly to your computer, using a stable connection.
3. Try extracting this new download locally. If it opens, you now have a clean copy.
4. Upload that clean file to your site’s wp-content/updraft folder via FTP or your host’s file manager.
5. Back in WordPress, go to Settings → UpdraftPlus Backups → Existing Backups and click Rescan local folder.
6. Once the backup appears again, retry the restore.

If the remote copy is also corrupted or incomplete, check whether:

• The original backup job was interrupted (server timed out, disk filled up, backup stopped mid way).
• Remote storage is full or throttling uploads.

If you still have access to the original live site (or a separate host level backup), the safest move is often:

1. Fix server resource issues (see Server side checks).
2. Run a fresh UpdraftPlus backup on the working site.
3. Download that new backup and try the restore again.

If the only copy is on this server

If there is no remote storage and the only backup lives in wp-content/updraft and that file is corrupted, there is unfortunately no guaranteed way to rebuild a valid ZIP.

Your options are:

• Check whether your host has their own backups you can restore from.
• See whether you have an older UpdraftPlus backup set where the same component opens correctly.
• As a last resort for large uploads archives, try extracting what you can locally and manually copying usable files back via FTP.

If you are in this situation and need help deciding the safest path, scroll down and hit Continue Chat so we can look at your exact scenario.

Step 4: Server side checks (if the zip opens locally)

If the archive opens fine on your computer but UpdraftPlus still logs PCLZIP_ERR_BAD_FORMAT (-10) during restore, something on the server is interfering with the unzip process.

Check free disk space

Unzipping a large backup temporarily needs substantial free space. If your disk is nearly full, WordPress may only write part of the extracted data before failing.

• In your hosting control panel, check how much free disk space you have.
• Delete old backups, unused themes and plugins, and large log files you no longer need.
• If you are close to your quota, ask your host to increase disk space.

Once you’ve freed up space, try the restore again.

Upload the backup manually and rescan

Sometimes the copy on the server is incomplete even though your local copy is fine.

1. Use FTP or your host’s file manager to rename the existing file in wp-content/updraft (for example, add .old to the filename).
2. Upload the clean ZIP from your computer into wp-content/updraft.
3. In WordPress, go to Settings → UpdraftPlus Backups → Existing Backups and click Rescan local folder.
4. When the backup appears with the correct size, retry the restore.

Check for memory limits or timeouts on huge archives

Very large uploads.zip or others.zip archives can hit PHP memory or execution time limits while unzipping. That can produce confusing errors in the log, including bad format messages.

• Increase memory_limit and max_execution_time in php.ini, .htaccess, or via your host’s UI.
• Temporarily disable strict security plugins that might kill long running PHP processes during restore.
• Retry the restore after increasing limits.

If large archives still fail consistently, you can also:

• Download the problematic ZIP, extract it locally, and upload the contents manually to the correct folder (for example, wp-content/uploads), then restore only the remaining components via UpdraftPlus.

Step 5: Re run the restore and verify

Once you either have a clean backup archive on the server or you have adjusted server limits, it’s time to try again.

Do this:

1. In WordPress, go to Settings → UpdraftPlus Backups → Existing Backups.
2. Click Restore on the backup set you just fixed.
3. Select only the components you actually need to restore (for example, just plugins and uploads).
4. Start the restore and watch the progress log.

You are in good shape when:

• The log finishes without any new PCLZIP_ERR_BAD_FORMAT (-10) entries.
• Your site loads normally after the restore.
• The restored files (plugins, themes, uploads, or others) match what you expect from that backup.

Short checklist

• You know which archive (database, plugins, themes, uploads, others) is triggering the error.
• You have tested that archive on your computer and confirmed whether it opens.
• If it was corrupted, you have re downloaded a clean copy from remote storage or created a new backup.
• If it was fine locally, you have checked disk space, re uploaded the file, and increased PHP limits if needed.
• The latest restore completes without PCLZIP_ERR_BAD_FORMAT (-10) in the UpdraftPlus log.

Still stuck?

For AI help

Hit Continue Chat below and paste the relevant part of your UpdraftPlus log, plus where your backups are stored. I’ll help you decide whether you can salvage this archive or need a different backup.

For expert human help

Scroll down to the contact form below. Enter your name, email, and WordPress needs. Atiba will get back to you as soon as possible.