If your Applet is quite big in size (over 5MB), you might experience an Error on Applet startup:
Blob not found The specified blob does not exist
Why it's happening
The reason is that the building process takes a bit long then the UI can handle and it allows you to start generating your signageOS Core App from this Applet sooner then all files are ready.
How to resolve it
To prevent this issue, kindly make sure you always wait for the build to finish.
You can check the status on the Applet detail page:
The final state is the following one: