This chapter summarizes error codes and open source components of VDDK. What to read next Recent ChangesIn vSphere 6.0, VDDK libraries were changed to return VIX_E_OUT_OF_MEMORY when an ESXi host run out of memory for network file copy (NFC). Previously, VDDK would hang during I/O. Finding Error Code DocumentationFor a list of Virtual Disk API error codes, see the online reference guide Introduction to the VixDiskLib API: Troubleshooting Dynamic Libraries Troubleshooting Changed Block Tracking (CBT)This section provides two hints for helping customers with CBT failures. Open Source ComponentsVDDK contains the following open source modules and others, with license types indicated: