PSEXEC, access denied errors

PsExec has whatever access rights its launcher has. It runs under regular Windows access control. This means whoever launched PsExec (be it either you, the scheduler, a service etc.) does not have sufficient rights on the target machine, or the target machine is not configured correctly. The first things to do are:

1. Make sure the launcher of PsExec is familiar to the target machine, either via the domain or by having the same user and password defined locally on both machines.
2. Use command line arguments to specify a user that is known to the target machine (-u user -p password)

If this did not solve your problem, make sure the target machine meets the minimum requirements, specified here.

I couldn't get access to remote machines unless I had UAC disabled.

That has to be done locally, either from control panel or running the following through cmd:

reg.exe ADD HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System /v EnableLUA /t REG_DWORD /d 0 /f

While UAC is enabled, make sure you run cmd as administrator.

For a different command I decided to change the network from public to work.
After trying to use the psexec command again it worked again.
So to get psexec to work try to change your network type from public to work or home.

I tried a lot of way but I could not use psexec. It gives "Access denied". After I change the target user account type from Standard to Admin, I connected the machine via psexec.

I researched the reason why admin type account is required then I found this answer.

You can change target machine user account this way: Control Panel -> User Accounts -> Change Account Type. You must enter an admin account and password to change that account if you logged in standard account.

After that I logged in with this command: psexec \\remotepcname -u remoteusername -p remotepassword cmd

Tried all suggestions above, but still was unable to resolve the error. Finally once I made the below change, I could successfully run the PSexec command.

Turns out that when you have UAC enabled psexec does not work as supposed. We need to set HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System\EnableLUA to 0 then psexec starts working as expected.