"Incompatible Archive" when uploading a plugin zip

When you upload a plugin .zip via Plugins → Add New → Upload Plugin, WordPress rejects it with:

Incompatible Archive. Return to the Plugin Installer

Reinstalling WordPress, switching browsers, or clicking "Return to the Plugin Installer" and retrying does not help — the same zip fails every time.

Why WordPress shows this

WordPress opens the uploaded .zip with its PclZip / ZipArchive reader before copying plugin files into wp-content/plugins/. If the reader cannot find a valid ZIP end-of-central-directory record, it aborts and surfaces "Incompatible Archive."

The usual cause is a corrupted or incomplete download — the zip on disk is not actually a complete zip file. Common triggers:

  • The download was interrupted (network blip, timeout, browser crash) and the saved file is truncated.
  • The browser silently decompressed the zip on download — macOS Safari and some browser extensions auto-extract .zip files, leaving either a folder or a re-zipped archive with a different structure.
  • The file was re-zipped after extraction (e.g. zipping the unzipped folder with macOS Finder), which nests the plugin inside a wrapper folder WordPress does not expect.
  • The file was edited or renamed in a way that changed its bytes — for example, opening it in an archive GUI and saving.

How to fix

  1. Delete the local .zip — don't trust the file on disk.
  2. Re-download from the original link we sent you. Let the download finish completely before doing anything else.
  3. Do not unzip it. WordPress expects the raw .zip, not an extracted folder or a re-zipped version.
  4. On macOS Safari, disable Preferences → General → Open "safe" files after downloading before downloading — this prevents auto-extraction. Or use Chrome / Firefox, which do not auto-extract.
  5. Upload the fresh .zip again via Plugins → Add New → Upload Plugin.

How to confirm the zip is intact

Before uploading, check the file size matches the one we sent. On the command line:

unzip -t wpc-site-installer.zip

A healthy zip prints No errors detected in compressed data. An "End-of-central-directory signature not found" or similar error confirms corruption — re-download.

Still stuck?

If a freshly downloaded zip still shows "Incompatible Archive," contact support@wpproconverter.com with your browser, OS, and the file size of the zip on disk, and we'll send you a replacement link.