The ownCloud software reports the following error:
No connection to ownCloud. Server has "403 Forbidden" on "PROPFIND ... (Unsupported client version.)
The cause of this error is that your ownCloud software installed (on PC, Mac) is outdated and a newer, up-to-date version is required.To do this, download a current version of the ownCloud desktop software (for Windows, Linux or Mac) and install it. Then restart your computer.