These error messages may have different reasons:
An action needs to much time, so the censhare default time out of 600 seconds is exceeded.
Solution: The time out can be configured role specific within the admin client in the client-preferences:
message_timeout_seconds="600" increase to 1200
An action needs to long due to damaged or problematic files.
Solution: Layout palette: the defect file can be found by right mouse button on the layout and "place used assets again".
If you do not get an error here, all placed assets are okay.
A dialog is in the background which prevents the communication between client and application.
Solution: Close the dialog and try again, please.
There is a 3rd-Party plugin which isn't supported (f.e. old version of suitcase plugin or Universal Type Client).
Solution: Please remove it.
The plugin was damaged. Please download and install the censhare plugins again.
Solution: Decompress the plugin archive not before it is in the desired target directory.
The censhare client is defect.
Solution: Please extract and install the client again.
On OS X Mojave you did not yet confirm the OS X access dialogs which request access between InDesign, client and vice versa.