A common cause of upload errors is an interruption in communication with eBay at the time an item is listing or being revised.
When an item is in status Upload Error, it means that Monsoon Marketplace attempted to list the item, but encountered a marketplace or technical issue that resulted in an error message confirming that the item failed to list.
An upload error may indicate a duplicate or abandoned listing and is commonly caused by an interruption in communication with eBay at the time an item is listing or being revised.
eBay Listing Synchronization overview
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