Hi guys,
I found the real reason now 
When I´m updating, I always delete all the files in /configurations folder and uploading my backup files over there. And that´s the problem since 1.8.x???
There is a file called “openhab_default.cfg” which defines nice little things like:
folder:items=10,items folder:sitemaps=10,sitemap folder:rules=10,rules folder:scripts=10,script folder:persistence=10,persist
Previous openhab versions seem to work without this config parameters. The current versions seem to ignore for example the sitemap file without this parameters.
Good to know 
Best regards,
Artur