I've suddenly started getting this message in my log files:
STRICT NOTICE: is_a(): Deprecated. Please use the instance of operator
This on different websites with different hosts. All using latest version of plugin and wordpress.
On one installation I also got this error and the backup failed (have tried several times):
ERROR: PclZip archive add error: PCLZIP_ERR_BAD_FORMAT (-10) : Unable to find End of Central Dir Record signature
Everything worked fine a few days ago.