I wrote a script that adds a function in a Google spreadsheet that was working well. From today, I get an error:

> 
> IO error when deserializing continuation.
> 
> 
> 

This appears after a call to `Ui.alert` or `Ui.prompt`. I tried to add sleep after the calls, but it doesn’t work. This is a sample of code:

```
ui.alert( "ERROR. !");
Utilities.sleep(1000);
return;

```