If you search the forum for "pcloud", you will surely find a more detailed answer and explanation, but the message is clear. If you want to continue with the synchronisation, you need to use a different sync provider. Or you can, at least temporarily, stay at the older version of Joplin for the time being until you manage to find a compatible one and migrate your data to it.
Really? Thanks for your response. There's nothing on the forum to suggest that a recent update to Joplin has rendered the function to synch with pCloud obsolete. So what have I missed? This setup worked until days / weeks ago.
If you want you can enable it again by opening database.sqlite in your profile, and setting the key sync.allowUnsupportedProviders to 1 in the settings table (or add the key if it's not already there). We no longer support pCloud because it can cause too many problems once you get to a certain number of notes.
I contacted pCloud's Technical Support regarding Joplin and pCloud's WebDAV. This is their response.
"We have a very basic version of WebDAV implemented, with no additional features. I can put in a request, but then I would need to know what Joplin needs, or what the issues with the pCloud WebDAV are that causes Joplin to be incompatible. We are not aware of numerous issues with our WebDAV implementation."
What does Joplin need as a compatible implementation of WebDAV, or what issues does Joplin have with pCloud's WebDAV?