Exception while invoking method 'update_document'

[loredanacirstea]

Exception while invoking method 'update_document' Error: When the modifier option is true, validation object must have at least one operator
I20170414-23:33:08.266(3)?     at checkModifier (packages/aldeed:simple-schema/simple-schema-validation.js:271:1)
I20170414-23:33:08.266(3)?     at doValidation1 (packages/aldeed:simple-schema/simple-schema-validation.js:321:1)
I20170414-23:33:08.266(3)?     at doValidation (packages/aldeed:simple-schema/simple-schema-context.js:9:1)
I20170414-23:33:08.266(3)?     at SimpleSchemaValidationContext.simpleSchemaValidationContextValidate [as validate] (packages/aldeed:simple-schema/simple-schema-context.js:44:1)
I20170414-23:33:08.266(3)?     at [object Object].doValidate (packages/aldeed:collection2/collection2.js:317:1)
I20170414-23:33:08.266(3)?     at [object Object].Mongo.Collection.(anonymous function) [as update] (packages/aldeed:collection2/collection2.js:154:1)
I20170414-23:33:08.266(3)?     at [object Object].Meteor.methods.update_document (app/lib/methods.js:25:40)
I20170414-23:33:08.266(3)?     at maybeAuditArgumentChecks (packages/ddp/livedata_server.js:1617:1)
I20170414-23:33:08.266(3)?     at packages/ddp/livedata_server.js:648:1
I20170414-23:33:08.266(3)?     at [object Object]._.extend.withValue (packages/meteor/dynamics_nodejs.js:56:1)
I20170414-23:33:08.266(3)?     at packages/ddp/livedata_server.js:647:1
I20170414-23:33:12.538(3)? { selected: 'null' }