I recently came across an ESXi install that was having trouble bringing a virtual machine online. The client had already tried to reboot the ESXi server but the problem remained.
Here is my problem, just about every website that you will find searching for this error will tell you that you need to "boot into linux mode" [vmware.com/thread/50436] or enable the CLI interface.
If you have already done this, great, but some clients dont want this, and in this case, doing so is totally un-needed. All you need to do to fix the error "could not power on vm no swap file" is as follows.
1.) Load the vmware infrastructure client, then click on the server and then choose the configuration tab.
2.) Select the Storage option under "Hardware"
3.) Select the storage device that the VM is stored on, right click and choose "browse datastore".
4.) Navigate to the VM's directory and find the file called "*server-name*.vswp", that is the VM's swap file. Click and remane it to the same name and append a .old DON'T DELETE IT.
5.) Start the VM, it will likely now complain about something is wrong with the snap shot. Shut the VM back down.
6.) Rename the .old back to the original name and restart the VM, TADA! It should now be working.
Hopefully this helps some folks, if it does, feel free to leave a comment below!