meaning of this error?

[bill]

this happens when i run multiple threads. can someone advise me on the best way to get around it?

 

[VladZen]

Something locks your .zpcookie file... I see it is in Dropbox directory... Is not it synched with dropbox someway?

 

[Nick]

Is there a specific block that's being executed while this error happens? Do you have a line from a red point that handles an error? You could add a Pause block and let it retry 10 times and then raise an error.
Make sure that Dropbox doesn't lock this file to update it.

 

[rostonix]

use it elsewhere rather then in shared folders