Synchronization of folder firstname.lastname@example.org/Contacts/
Failed to upload contact “Contact Name”
The contact was modified both on the remote server and locally. You can either download the contact from server, losing your local changes, or overwrite the contact on server causing server changes to be lost. Which action do you you want to take?
The warning message is actually a feature of eM Client to safeguard the integrity of the data, especially when the changes can be made from multiple devices or multiple locations, such as through web browser and smartphone at the same time.
However, the issue above most commonly happens because of making too many changes too fast. For example, amending and saving the contact quickly for a few times within minute. When eM Client doesn’t manage to upload the previous changes to the cloud server before the new change is made, it will ask if you want to save or discard the latest change.
Thus, just go slow when editing the contacts, or save only once after all changes are made and you will not see the prompt anymore.