If you are having a problem using Winscp to upload files to the vCenter Server Appliance (VCSA), you should change some settings on the Winscp client or the VSCA appliance, it depend on what protocol you are using SFTP or SCP.
Using SFTP:
When opening a connection to VCSA, you get the following error:
Host is not communicating for more than 15 seconds. Still waiting. Note If the problem repeats, try turning off 'Optimize connection buffer size'.
To fix this, go to the “Advanced” window and change the SFTP protocol setting like this:
1- 
2-
Using SCP:
When opening a connection to the VCSA,using SSH/SCP, you get the following error:
Error skipping startup message, Your shell is probably incompatible with the application (BASH is recommended).
The VCSA use a proprietary shell script to lunch some python scripts to setup the environment, as shown her:
To fix this, connect to the vCenter Server Appliance using Putty/SSH and enable the shell:
Command> shell.set --enabled True Command> shell #
Then change the shell for the root user to use bash
chsh -s /bin/bash root
This will allow you to use Winscp to transfer files from the VCSA using SCP.
You can change back the shell for the root user after that:
chsh -s /bin/appliancesh root