Hyper-V: An error occurred while attempting to export the virtual machine.

When you try to export Hyper-V Virtual machine to network share you get this error:

An error occurred while attempting to export the virtual machine. 
Failed to copy file during export.

General access denied error (0x80070005)

Solution:
Computer account of Hyper-V host should have permissions on NTFS and share level to write to target network share:

NTFS permissions:

1.  On the destination server, Right-click on the shared folder and select Properties. 
2.  Select the Security tab. 
3.  Click Edit button and click the Add button in the permissions dialog box. 
4.  Click Oject Types and select Computers if not already done and click OK.
5.  In the dialog "Enter the object names to select" provide the name of Hyper-V host machine and click Check Names.
6.  With the Hyper-V host machine name select, click Allow by "Full control" and click OK.

Share  permissions:

1.  On the destination server, Right-click on the shared folder and select Properties. 
2.  Select the Sharing tab. 
3.  Click Advanced Sharing...
4.  On the Advanced Sharing dialog, click Permissions  and then Add.

5. Click Oject Types and select Computers if not already done and click OK.
6.  In the dialog "Enter the object names to select" provide the name of Hyper-V host machine and click Check Names.7.  With the Hyper-V host machine name select, click Allow by "Full control" and click OK.