Sometimes we get IO exceptions on umbraco.config. Stack trace below. The error stays until I restart the website. It is hosted on Azure and we use Umbraco version 7.2.5 assembly: 1.0.5610.18894 (we will update soon).

As I understand, umbraco.config is used for caching. I've recently added some caching to the website with the following code:

var cache = ApplicationContext.Current.ApplicationCache.RuntimeCache;
            var cachedItem = cache.GetCacheItem(key);

            if (cachedItem == null)
        {
         .... some code....

            var toReturn = items.OrderByDescending(i => i.GetPropertyValue("date")).Take(5);
            cache.InsertCacheItem(key, () => { return toReturn; }, TimeSpan.FromHours(_cachingDuration));

            return toReturn;

        }

        return cachedItem as IEnumerable<DynamicNode>;

Could this be the cause of the IO exception? Does anyone know how to fix this or should I log it as a bug?

  An unhandled exception occurred
    System.IO.IOException: The process cannot access the file 'D:\home\site\wwwroot\App_Data\umbraco.config' because it is being used by another process.
    at System.IO.__Error.WinIOError(Int32 errorCode, String maybeFullPath)
    at System.IO.File.InternalDelete(String path, Boolean checkHost)
    at System.IO.File.Delete(String path)
    at umbraco.content.DeleteXmlFile()
    at umbraco.content.LoadXmlFromFile()
    at umbraco.content.LoadXmlLocked(SafeXmlReaderWriter safeXml, Boolean& registerXmlChange)
    at umbraco.content..ctor()
    at umbraco.content.<.cctor>b__14()
    at System.Lazy`1.CreateValue()
    --- End of stack trace from previous location where exception was thrown ---
    at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
    at System.Lazy`1.get_Value()
    at Umbraco.Web.PublishedCache.XmlPublishedCache.PublishedContentCache.<get_GetXmlDelegate>b__3(UmbracoContext context, Boolean preview)
    at Umbraco.Web.PublishedCache.XmlPublishedCache.PublishedContentCache.GetXml(UmbracoContext umbracoContext, Boolean preview)
    at Umbraco.Web.PublishedCache.XmlPublishedCache.PublishedContentCache.HasContent(UmbracoContext umbracoContext, Boolean preview)
    at Umbraco.Web.PublishedCache.ContextualPublishedCache`1.HasContent(Boolean preview)
    at Umbraco.Web.UmbracoModule.EnsureHasContent(UmbracoContext context, HttpContextBase httpContext)
    at Umbraco.Web.UmbracoModule.EnsureUmbracoRoutablePage(UmbracoContext context, HttpContextBase httpContext)
    at Umbraco.Web.UmbracoModule.ProcessRequest(HttpContextBase httpContext)
    at Umbraco.Web.UmbracoModule.<Init>b__a(Object sender, EventArgs e)
    at System.Web.HttpApplication.SyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
    at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)