fdopendir: Permission denied when running updatedb

I'm trying to index the files on my NAS (It's a TerraMaster F4-210) with the command: updatedb -l 0 -o /home/jake/nas-index.db -U /mnt/nas/ After running for a little while it dies with the error: fdopendir: Permission denied No file is created at /home/jake/nas-index.db It was mounted with the command: mount -t cifs -o "username=jake,password=mypass" //10.0.0.127/jake /mnt/nas/ mount | grep nas //10.0.0.127/jake on /mnt/nas type cifs (rw,relatime,vers=3.1.1,cache=strict,username=jake,uid=0,noforceuid,gid=0,noforcegid,addr=10.0.0.127,file_mode=0755,dir_mode=0755,soft,nounix,mapposix,rsize=4194304,wsize=4194304,bsize=1048576,echo_interval=60,actimeo=1) and my user can read and write to it. For example I can do: $> cd /mnt/nas $> ls -al myfile.txt ls: cannot access 'myfile.txt': No such file or directory $> touch myfile.txt $> ls -al myfile.txt -rwxr-xr-x 1 root root 0 Feb 24 01:36 myfile.txt* $> cat myfile.txt $> echo "foo" >> myfile.txt $> cat myfile.txt foo $> rm myfile.txt $> ls -al myfile.txt ls: cannot access 'myfile.txt': No such file or directory So I can create, append, read, and delete the file. I have even tried running the updatedb command as root. To make sure I'm not accidentally ignoring the path or filesystem, I have commented out everything in /etc/updatedb.conf. I'm not sure what to try next. What is going on and how do I fix it? Thanks in advance.