Description

Error messages related to the media cache may occur in Sitecore log files in various scenarios, such as:

• When media items that are not yet cached in the file-based media cache get simultaneously accessed by multiple users.
• When media items are accessed by users and antivirus or other external software locks the file system, preventing Sitecore from properly updating the file-based media cache.

The following errors can occur:

ERROR OpenFileStream failed: C:\inetpub\wwwroot\sc660rev130111WebApi\Website\App_Data\MediaCache\website\202\6f9ce455d0cc4e6f8a2d2862c016e8b8.jpg
Exception: System.IO.IOException 
Message: The process cannot access the file 'C:\inetpub\wwwroot\sc660rev130111WebApi\Website\App_Data\MediaCache\website\202\6f9ce455d0cc4e6f8a2d2862c016e8b8.jpg' because it is being used by another process.
Source: mscorlib
at System.IO.__Error.WinIOError(Int32 errorCode, String maybeFullPath)
at System.IO.FileStream.Init(String path, FileMode mode, FileAccess access, Int32 rights, Boolean useRights, FileShare share, Int32 bufferSize, FileOptions options, SECURITY_ATTRIBUTES secAttrs, String msgPath, Boolean bFromProxy, Boolean useLongPath, Boolean checkHost)
at System.IO.FileStream..ctor(String path, FileMode mode, FileAccess access, FileShare share, Int32 bufferSize, FileOptions options, String msgPath, Boolean bFromProxy)
at System.IO.FileStream..ctor(String path, FileMode mode, FileAccess access, FileShare share)
at Sitecore.IO.FileUtil.OpenFileStream(String filePath, FileMode mode, FileAccess access, FileShare share, Boolean createFolder, Boolean logErrors)

ERROR Could not add media to cache. Media item id: {C9276AE7-7ABB-47B0-8C26-99F669A52CF5}
Exception: System.InvalidOperationException 
Message: Could not create the buffer file needed for stream sharing.
Source: Sitecore.Kernel 
at Sitecore.IO.StreamSharer..ctor(Stream masterStream, String bufferFilePath)
at Sitecore.Resources.Media.MediaCacheRecord.Initialize(Media sitecoreMedia, MediaOptions mediaOptions, MediaStream mediaStream)
at Sitecore.Resources.Media.MediaCache.CreateCacheRecord(Media media, MediaOptions options, MediaStream stream)
at Sitecore.Resources.Media.MediaCache.AddStream(Media media, MediaOptions options, MediaStream stream, MediaStream& cachedStream)
at Sitecore.Resources.Media.Media.AddStreamToCache(MediaOptions options, MediaStream mediaStream, MediaStream& cachedStream)

Solution

This issue does not affect the site's functionality for the end users. Corresponding media requests will be processed properly, bypassing the Sitecore file-based media cache and transferring media data directly from the database.

For the antivirus scenario, it is recommended to configure the antivirus to ignore file system updates in the \App_Data\MediaCache folder.