HTTP Error 500.19 - Internal Server Error After CIFS mount

Web site had been running normally on Windows IIS 10 and .net 3.5 until the web site root directory was shared and was then mounted on Ubuntu via: $ sudo mount -t cifs -o username=,password= //IP/fis /mnt/share

Error Code: 0x80070005 Config Error: Cannot read configuration file due to insufficient permissions \?\D:...\web.config

After hours of googling and trying, I finally solved the problem by using workarounds.

I zipped the web directory and transfer to my Linux notebook. Unzipped it and zipped again on Ubuntu. I then transferred the new zipped file back to Windows. I unzipped it to a a folder which had not ever been mounted via SMB/CIFS. I created a new web site on the ever new folder and used a new pool. Everything was new and everything worked.

I removed all shares but the problem did get resolved until I used the above workaround. Is this a sever bug of IIS?