Item Specific value must be not more than 65 characters

eBay will return this error if the value used for an Item Specific field is too long. It should be 65 characters or fewer. 

Please check the values you provided for the Item Specifics and edit those that do not meet the requirements. Here is where you can find the list of the Item Specifics set for an eBay category in M2E Pro:

1. eBay > Configuration > Categories and click View next to the category that the affected products are listed in. Here you can see what values or Magento attributes are set for the Item Specifics and adjust them to satisfy eBay requirements.

2. Alternatively, you can update them inside an M2E Pro Listing. Go to Listing, switch the View Mode to Settings, filter out the affected products by category, and select Edit Category Settings in the Actions drop-down.

Please remember to Save the changes after edits to the Item Specifics settings are made.