I recently had the same problem when trying to expand the memory of a Linux VM from 8GB to 16GB.
In mine I managed to solve it using the Flash version of Vcenter, but as it is no longer supported I followed this tutorial to access it in Flash mode:
https://www.reddit.com/r/flash/comments/l5r6fs/tutorial_how_to_run_flash_in_a_web_browser_with/
I'm using vcenter with vsphere 6.5.
Att,
Junior Cesar
