It's been a while since I uploaded my latest screenshot to Steam, because mere 4 gigabytes of cloud space granted by Valve got exhausted really fast. In the meantime I still continued to take screenshots, with Steam and with other tools, saving them locally and patiently waiting when upload limits are increased, so I can upload all this stuff again.

And the screenshot space finally got increased to whopping **20 GB**! This means we can now upload tons of screenshots we made since the last cloud space bump.

But unfortunately something has changed and now I can't upload any old screenshots. I wrote "custom" in the question's title, but in my case screenshots are custom basically because they were taken with some third party utility or even with `PrtScr` and `Ctrl` + `V`.

The new naming scheme is `YYYMMDDHHMMSS_1.jpg`, files are still saved to `C:\Program Files (x86)\Steam\userdata\<user id>\<some number>\remote\<game id>\screenshots`, and when you place your custom screenshots to this folder, Steam screenshot uploader sees them, creates thumbnails, but refuses to upload. Now it only uploads screenshots actually taken with Steam.

So guides like [this one](https://steamcommunity.com/sharedfiles/filedetails/?id=221925378) became obsolete. The notorious "Steam Cloud may be temporarily unavailable" error appears. I'm sure custom screenshots still can be uploaded, but the whole process apparently now is more tricky.

Anyone able to crack this for us screenshotheads?