A great Dropbox file exclusion trick no longer seems to work.

My Thunderbird profile is in Dropbox, mainly because I have years of historical email in the locally stored "Local Folders", so it is all synced to Dropbox in case of drive failure. But the file "parent.lock" that is opened when Thunderbird is running can't be synced by Dropbox, so just recently, probably because of some update, Dropbox is running high CPU repeatedly trying to sync the open file.

There used to be a great trick of creating a folder with the same name as a file you did not want to sync, and then excluding it from sync with the Dropbox "selective sync" feature, explained here, and then putting the file back, whereupon it would not be synced because it had the same name as the excluded folder.

However, I just tried it, and when you exclude the folder with selective sync, Dropbox now says "deselected files will only be available on Dropbox.com". So instead of removing the folder completely from sync and ignoring it, it puts it in cloud storage but remembers it. Then the moment you add the file back, with the same name as the folder, you get a conflict file created by Dropbox, and then it tries to sync the file again.

I tried deleting the cloud only folder on the Dropbox website, and trying the trick again, but that makes Dropbox forget about the sync exclusion, and the same thing happens all over again.

Can the trick in the link above still be done somehow? Somehow selectively exclude a folder from sync, but not put it in cloud storage, and just completely ignore that name?

EDIT: Ref my comment on the answer by @harrymc below, I could not figure out how to add the details to my comment, so add them here - the error I received:

PS C:\WINDOWS\system32> Set-Content -Path 'C:\Dropbox\System_Folder\Applications\Thunderbird\Profiles\profile.wms\parent.lock' -Stream com.dropbox.ignored -Value

Set-Content : Missing an argument for parameter 'Value'. Specify a parameter of type 'System.Object[]' and try again.

At line:1 char:132

+... \Profiles\profile.wms\parent.lock' -Stream com.dropbox.ignored -Value

+ CategoryInfo          : InvalidArgument: (:) [Set-Content], ParameterBindingException
+ FullyQualifiedErrorId : MissingArgument,Microsoft.PowerShell.Commands.SetContentCommand

1 Answer 1


From the Dropbox Help article How to set a file or folder to be ignored:

  1. Open the PowerShell application on your computer.

  2. Type the code below, replacing the file/folder path placeholder with the file/folder path you’d like to ignore.

    Set-Content -Path 'C:\Users\yourname\Dropbox(Personal)\YourFileName.pdf' -Stream com.dropbox.ignored -Value 1
  3. Press enter on your keyboard.

The icon beside your file or folder will change to a gray minus sign indicating that it has been ignored.

  • Thanks. Embarrassing when the answer is in the help file. However, I got an error. There was not room to provide it here, so I edited my post above with the details. Apologies if this is not the correct procedure. Nov 4, 2023 at 1:59
  • There seems to be an error in the documentation, it should be : -Value 1. Corrected in my answer.
    – harrymc
    Nov 4, 2023 at 8:52
  • Thanks, that worked. I have contacted Dropbox support with a request to update their help page. The power of a team! Nov 4, 2023 at 11:47

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