CryptoPro Browser Plugin. Why is an "Access denied" exception thrown when signing data?

Question

JavaScript

Good afternoon.
To sign documents in the browser, we use the CryptoPro Browser Plugin.
When executing the following code:

var oSigner = cadesplugin.CreateObject("CAdESCOM.CPSigner");
oSigner.Certificate = oCert;
var oSignedData = cadesplugin.CreateObject("CAdESCOM.CadesSignedData");
oSignedData.ContentEncoding = 0x01;
oSignedData.Content = dataToSign;
var sSignedMessage = oSignedData.SignCades(oSigner, 1);

some users are throwing an exception:

Access denied (0x80090010)

on line

var sSignedMessage = oSignedData.SignCades(oSigner, 1);

So far, no patterns have been found between these users. Who faced and can tell what's the matter?