OctoPrint v1.3.11 is available since few days and, some users noticed that their STL files disappeared from Printoid.
In fact, they are also missing from your OctoPrint web interface, and the reason is simple: OctoPrint is no more bundled with CuraEngine.
So, in order to support STL & slicing using Cura Engine, you need to install the CuraEngine Legacy plugin by yourself. Here is a quick tutorial:
1/ From the OctoPrint web app, open the settings:
2/ Select the “Plugin Manager” menu and search for CuraEngine Legacy:
3/ Click on “Install”and wait for completion
4/ Restart your OctoPrint server
After that, your STL files will be back in your OctoPrint web app (if you had some STL files before updating to OctoPrint v1.3.11) and they will be available again in Printoid too.