Web Connector Error: This List Has Been Modified by Another User

During a Web Connector sync, QuickBooks Desktop can reject a request with this message:

This list has been modified by another user ...

QuickBooks Desktop can also show a related message instead, depending on which record it was updating when the conflict occurred.

Example: "Object cannot be added" or "There was an error when saving a fieldValue."

Why This List-Locking Error Happens

This error comes from QuickBooks Desktop itself, not from Maxio Platform. It appears to be a random locking issue tied to certain versions of QuickBooks Desktop, where QuickBooks Desktop's own list-locking mechanism briefly treats a list as being modified by another user, even when no other user or application is actually working in the company file at the time. Because the lock lives entirely inside QuickBooks Desktop's own list-management behavior, this is third-party behavior that Maxio's codebase has no visibility into and cannot confirm or verify.

Wait and Retry, or Restart QuickBooks Desktop

Because the lock tends to clear on its own, the fix is almost always patience before it's troubleshooting.

To clear the QuickBooks Desktop locking issue

1. Wait a few minutes, then try the sync again.
2. If the error returns, wait a substantial period of time, such as an hour, before trying again.
3. If the error still doesn't clear, close QuickBooks Desktop entirely and restart it, then try the sync again.

Related information

If instead you're seeing a message about the company file itself being locked by another client, see Company File Is Locked by Another Client Running at Machine Named for that separate locking scenario that Maxio also cannot override.