jenkinsci/jenkins · warning · Failure

{0} is not a Jenkins plugin

Error message

{0} is not a Jenkins plugin

What it means

Failure thrown when a file upload during plugin installation does not have a .jpi or .hpi extension. The message comes from hudson.model.Messages.Hudson_NotAPlugin. Jenkins only accepts Jenkins Plugin Interface (.jpi) or legacy Hudson Plugin Interface (.hpi) archives.

Source

Thrown at core/src/main/java/hudson/PluginManager.java:1944

            List<DiskFileItem> items = upload.parseRequest(req);
            String string = items.get(1).getString();
            if (string != null && !string.isBlank()) {
                // this is a URL deployment
                fileName = string;
                copier = new UrlPluginCopier(fileName);
            } else {
                // this is a file upload
                FileItem fileItem = items.getFirst();
                fileName = Util.getFileName(fileItem.getName());
                copier = new FileUploadPluginCopier(fileItem);
            }

            if ("".equals(fileName)) {
                return new HttpRedirect("advanced");
            }
            // we allow the upload of the new jpi's and the legacy hpi's
            if (!fileName.endsWith(".jpi") && !fileName.endsWith(".hpi")) {
                throw new Failure(hudson.model.Messages.Hudson_NotAPlugin(fileName));
            }

            // first copy into a temporary file name
            File t = File.createTempFile("uploaded", ".jpi", tmpDir);
            tmpDir.deleteOnExit();
            t.deleteOnExit();
            // TODO Remove this workaround after FILEUPLOAD-293 is resolved.
            Files.delete(Util.fileToPath(t));
            try {
                copier.copy(t);
            } catch (Exception e) {
                // Exception thrown is too generic so at least limit the scope where it can occur
                throw new ServletException(e);
            }
            copier.cleanup();

            final String baseName = identifyPluginShortName(t);

View on GitHub (pinned to 2e228ff40b)

Solutions

1. Ensure the uploaded file is a valid Jenkins plugin archive (.jpi).
2. If building a custom plugin, run 'mvn hpi:hpi' or 'mvn package' to produce the .hpi/.jpi.
3. Validate the file extension before uploading in automation scripts.

Example fix

// before
File file = new File("my-plugin.zip");
// upload fails: not a Jenkins plugin

// after
File file = new File("my-plugin.jpi");
// ensure it was built with: mvn hpi:hpi

if (!fileName.endsWith(".jpi") && !fileName.endsWith(".hpi")) {
    throw new IllegalArgumentException("File must be a .jpi or .hpi plugin archive: " + fileName);
}

public static boolean isJenkinsPluginArchive(String fileName) {
    return fileName != null && (fileName.endsWith(".jpi") || fileName.endsWith(".hpi"));
}

When it happens

Trigger: Uploading a file via the plugin upload form (doUpload) where the filename does not end in .jpi or .hpi — e.g., .zip, .jar, .tar.gz, or a file with no extension.

Common situations: A user accidentally uploads a generic JAR, ZIP, or the wrong file type through the Advanced > Upload Plugin form; or an automated deployment script sends the wrong archive.

Related errors

• Ambiguous plugin: {0}
• No such plugin: {0}
• Malformed plugin attribute: {0}
• Null value not allowed as an environment variable: ${key}
• invalid iconSize

AI-assisted analysis of jenkinsci/jenkins@2e228ff40b (2026-08-14). Data as JSON: /api/errors/e324f657dcbc87b6. Report an issue: GitHub.