收集在Windows Phone 8应用程序

Question

这是我在单独存储中保存设置的代码。

  public bool AddOrUpdateValue(string Key, Object value)
    {
        bool valueChanged = false;

        // If the key exists
        if (settings.Contains(Key))
        {
            // If the value has changed
            if (settings[Key] != value)
            {
                // Store the new value
                settings[Key] = value;
                valueChanged = true;
            }
        }
        // Otherwise create the key.
        else
        {
            settings.Add(Key, value);
            valueChanged = true;
        }
        return valueChanged;
    }

 public void SaveCurrentTime()
    {

        if (AddOrUpdateValue("DeactivateTime", DateTimeOffset.Now))
        {
            settings.Save();
        }
    }

但有时我会收集修改后的异常。查找以下异常详情

  

[Type]：[InvalidOperationException] [ExceptionMessage]：[Collection is   改性;枚举操作可能无法执行。] [StackTrace]：[at   System.ThrowHelper.ThrowInvalidOperationException（ExceptionResource   资源）   System.Collections.Generic.Dictionary`2.Enumerator.MoveNext（）at   WriteArrayOfKeyValueOfstringanyTypeToXml（XmlWriterDelegator，Object，   XmlObjectSerializerWriteContext，CollectionDataContract）at   System.Runtime.Serialization.CollectionDataContract.WriteXmlValue（XmlWriterDelegator   xmlWriter，Object obj，XmlObjectSerializerWriteContext context）at   System.Runtime.Serialization.XmlObjectSerializerWriteContext.WriteDataContractValue（DataContract   dataContract，XmlWriterDelegator xmlWriter，Object obj，   RuntimeTypeHandle declaredTypeHandle）at   System.Runtime.Serialization.XmlObjectSerializerWriteContext.SerializeWithoutXsiType（DataContract   dataContract，XmlWriterDelegator xmlWriter，Object obj，   RuntimeTypeHandle declaredTypeHandle）at   System.Runtime.Serialization.DataContractSerializer.InternalWriteObjectContent（XmlWriterDelegator   writer，Object graph，DataContractResolver dataContractResolver）at   System.Runtime.Serialization.DataContractSerializer.InternalWriteObject（XmlWriterDelegator   writer，Object graph，DataContractResolver dataContractResolver）at   System.Runtime.Serialization.XmlObjectSerializer.WriteObjectHandleExceptions（XmlWriterDelegator   writer，Object graph，DataContractResolver dataContractResolver）at   System.Runtime.Serialization.XmlObjectSerializer.WriteObject（的XmlDictionaryWriter   作家，对象图）   System.Runtime.Serialization.XmlObjectSerializer.WriteObject（流   流，对象图）   System.IO.IsolatedStorage.IsolatedStorageSettings.Save（）

谁能告诉我哪里出错了？