This update, done on the morning of 26/06/2016, shows some incompatibilities with our scripts or the Advanced Custom Fields plugin. The database seems intact and is, in any case, backed up. Just bear with me until I resolve the issues.
A frequent message states that the function get_currentuserinfo() is deprecated and should be replaced by wp_get_current_user(). This is of no consequence except that it appears in some pages and adds to the error log.
[update]Our scripts have been changed to use the recommended function and the problem is now resolved.