"I/O Error Occurred" in vSphere Client working with ESXi

I have a datastore set up in ESXi where I put all my ISOs. Somehow, something broke (I don't know what) and now I can't upload files to that (or any other) datastore. For large, ISO-sized files, the "Uploading..." dialog pops up, hangs for a while, and then the "I/O Error Occurred" displays. For smaller files (10 meg neighborhood), the "Uploading..." dialog comes up, a progress bar starts going, and it estimates a time remaining. Then it hangs at 1 second remaining for a while, and the same "I/O Error Occurred" comes up.

Has anyone seen a problem like this?

Solution 1:

There have been known issues with ESXi's datastore browser (and other file transfer methods) throwing this error sometimes intermittently, sometimes only for large files - I haven't ever seen a definitive fix for all cases but many seem to be related to network hardware. I've never seen the issue but I've only ever installed ESXi on fully certified hardware. What is the hardware config that you are using, which NIC's in particular and were any of the changes you might have made possibly related to the NIC settings or drivers (ie did you run an update)?