Folders that are unchecked in selective sync preferences will be removed from the Dropbox folder on your hard drive. However, if you create a folder with the same name as an unsynced folder, the new folder will have a gray circle with a minus sign on it. This icon indicates the folder isn’t syncing to Dropbox.
Example of a selective sync conflict
To see how a selective sync conflict could happen, imagine you create a folder called "Taxes." If you uncheck "Taxes" in your selective sync preferences, this will stop "Taxes" from syncing to the Dropbox folder on your computer. If you then create a new folder called "Taxes," it will appear with a gray minus sign, and Dropbox won't sync that folder.
If you resume syncing both the original "Taxes" folder and the new "Taxes" folder, the name of the "Taxes" folder with the minus sign will be appended with "(Selective Sync Conflict)." Both the old and new folders will sync to your account on dropbox.com.
To remove the folder with the gray minus sign
To remove the "Selective sync conflict" folder
Selective sync is unavailable while Dropbox is paused or in the process of syncing files. This means that if you're running the Dropbox desktop app for the first time, you may have to wait until Dropbox has finished indexing the files in your Dropbox folder before you can access selective sync settings.
If you see the message "Performing initial sync with server. Please wait…" it means the Dropbox desktop app is in the process of indexing the files in your Dropbox folder, or that you paused syncing from the Dropbox menu. If either of these are true, you can choose to wait until indexing is complete to access your selective sync settings. Otherwise, select Cancel to dismiss the message and return to your preferences window. If you paused syncing, you can resume at any time.
Dropbox will continue indexing (as indicated by the icon with rotating arrows over your Dropbox icon) and you'll still be able to browse and change other preferences while Dropbox finishes.
Dropbox might not update your selective sync preferences if any of the following are true:
Check your available hard drive space
It's possible that there's no room to save the data that's necessary to update your selective sync preferences. To see if this is the case, check your available hard drive space. If your hard drive is very low on disk space, you may need to first make space available outside of the Dropbox folder.
Files or folders are in use
Dropbox is not able to selectively sync folders if they (or the files they contain) are being used in other applications. To resolve this issue, close any applications that are accessing files in your Dropbox folder before attempting to update your selective sync preferences.
You’re using symlinks or referenced files
We strongly recommend against methods that add referenced files (symlinks, junction points, or networked folders) to the Dropbox folder. In addition to interfering with updating Selective Sync preferences, reference files can cause high CPU usage, poor syncing performance, permissions issues, and space usage discrepancies.
Incorrect file permissions
If files in your Dropbox don't have correct permissions, Dropbox may not sync them. Select your operating system below to troubleshoot file permissions:
icacls "D:\Dropbox" /grant "%USERNAME%":(F) /T
icacls "%HOMEPATH%\Dropbox" /grant "%USERNAME%":(F) /T icacls "%APPDATA%\Dropbox" /grant "%USERNAME%":(F) /T
sudo chflags -R nouchg ~/Dropbox ~/.dropbox ~/.dropbox-master sudo chown "$USER" "$HOME" sudo chown -R "$USER" ~/Dropbox ~/.dropbox sudo chmod -RN ~/.dropbox ~/Dropbox chmod -R u+rw ~/Dropbox ~/.dropbox
sudo chown "$USER" "$HOME" sudo chown -R "$USER" ~/Dropbox ~/.dropbox sudo chattr -R -i ~/Dropbox sudo chmod -R u+rw ~/Dropbox ~/.dropbox