Fix Requested NFS version or transport protocol is not supported

Through this post you should be able to solve/fix requested nfs version or transport protocol is not supported. This is caused because of nfs client tries to connect via nfs v4 but the server doesn't support it.

So below is a brief talking about the error and how you can get around it.

To be exact you got this error when trying to mount a NFS drive (nfs server on Windows 10 Pro.)

mount.nfs: timeout set for Mon Nov 18 11:19:17 2019
mount.nfs: trying text-based options 'vers=4.2,addr=192.168.1.64,clientaddr=192.168.1.242'
mount.nfs: mount(2): Operation not supported
mount.nfs: trying text-based options 'vers=4.2,addr=192.168.1.64,clientaddr=192.168.1.242'
mount.nfs: mount(2): Operation not supported
mount.nfs: trying text-based options 'vers=4.2,addr=192.168.1.64,clientaddr=192.168.1.242'
mount.nfs: mount(2): Operation not supported
mount.nfs: requested NFS version or transport protocol is not supported

So, basically when we are using nfs-utils package to mount the nfs shared directory. By default it tries to connect using the latest protocol that is v4. But on the server side our nfs server on Windows 10 Pro doesn't support it. WinNFSd is the program we are using to setup nfs server on our Windows system, that only supports v2 or v3 nfs protocol.

Read also: Setting up NFS server on Non-server Windows and Mount on Linux

To fix it we just need to do is tell the nfs client to use the nfs protocol v3 or v2. For that you will need to edit the nfsmount.conf file. And the default version to 3.

sudo nano /etc/nfsmount.conf

Find the section with # Protocol Version [2,3,4]. And look for # Defaultvers= line.
Now uncomment the Defaultvers line and set it to 3 like below.

After that try to mount and it should be working now. Below is a little video about the same error. This is how you Fix Requested NFS version or transport protocol is not supported on Linux.