Resolving Gravity Forms Dropbox Upload Issues: A Comprehensive Troubleshooting Guide

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Troubleshooting Gravity Forms Dropbox Integration Issues: Resolving Session and Temporary Directory Problems

Updating plugins, such as Gravity Forms, can occasionally cause integration issues with add-ons like Dropbox. A recent technical issue we resolved involved the Gravity Forms Dropbox add-on failing to upload submissions post-update, some of the submissions were 60-100mb so large files. We initially assumed it was a API key, timeout or firewall issue (as everyone typically does) however the logs gave us insight into a much more complex issue.

Problem Overview

Following the update of Gravity Forms and its Dropbox add-on, file uploads to Dropbox ceased working. The debug logs showed repeated nonce errors and occasional cURL timeouts:

ERROR --> GF_Dropbox::verify_nonce(): Aborting. Unable to verify nonce.
ERROR --> GF_Dropbox::maybe_process_feed_on_post_request(): Unable to verify nonce; ignoring processing request.

And:

cURL error 28: Operation timed out after 1001 milliseconds with 0 bytes received

Troubleshooting Steps and Analysis

1. Reconnecting Dropbox App

The Dropbox integration was disconnected and reconnected via the Gravity Forms settings interface to regenerate OAuth credentials. This did not resolve the issue.

2. Verifying Dropbox API Permissions

The Dropbox app permissions were verified and confirmed to include:

  • files.content.write
  • sharing.write

Permissions were correct and ruled out as the cause.

3. Rolling Back Gravity Forms Plugin

Gravity Forms was temporarily rolled back to an earlier stable version to rule out compatibility issues. The upload issue persisted, confirming the problem was not version-specific.

4. Server Performance Optimization

Server PHP and resource configurations were reviewed and updated to:

  • max_execution_time: 2000 seconds
  • default_socket_timeout: 300 seconds
  • memory_limit: 2G

These changes did not resolve the upload issues, indicating server resources were sufficient.

5. Testing Network Connectivity via SSH

SSH access was used to verify network connectivity to Dropbox API endpoints explicitly:

ping api.dropboxapi.com
ping content.dropboxapi.com
curl -Iv https://api.dropboxapi.com
curl -Iv https://content.dropboxapi.com

Endpoints were accessible, ruling out network connectivity problems.

6. PHP Session Investigation

Attention shifted to PHP sessions due to persistent nonce errors. An SSH check of the /tmp directory revealed session files of 0 bytes, indicating corrupt sessions:

ls -lah /tmp | grep sess
-rw-------  1 user user    **0** May 29 04:41 sess_ebvcq6p246qhdrel7b1addju69

Resolution

To resolve the session issues:

  • A dedicated PHP session directory was created explicitly within the site directory:
mkdir -p /home/username/public_html/tmp
chmod 755 /home/username/public_html/tmp
  • PHP sessions were explicitly directed to this directory by modifying wp-config.php:
ini_set('session.save_path', '/home/username/public_html/tmp');
  • Old corrupted session files were cleared:
rm -f /tmp/sess_*
  • PHP session functionality was verified using a test script (session-test.php):
<?php
session_start();
$_SESSION['test'] = 'ok';
echo "Session Path: " . ini_get('session.save_path');
?>

The test confirmed sessions were correctly saved:

ls -lah /home/username/public_html/tmp
-rw-------  1 user user   14 May 29 05:31 sess_qsj0imuata9l3ptgcroe619t7j

Final Verification

After correcting session storage, Gravity Forms Dropbox uploads functioned correctly without nonce or timeout errors.

Conclusion

The Gravity Forms Dropbox integration issue stemmed from corrupt PHP sessions in the shared /tmp directory. By explicitly defining a secure, user-level PHP session directory and ensuring PHP used this path, the nonce verification issue was effectively resolved. This troubleshooting emphasizes the importance of verifying session integrity when facing nonce-based security errors in WordPress plugin integrations.