can not execute a script:permission denied, although it has the execution flag set (-rwxr-xr-x)

[robert rottermann]

Hi there

in a folder on my desktop with Ubuntu 20.04 i can not execute any script that 
has the execution flag set.

But an attempt to run it, fails with an permission error:

robert at chrissy:~/Dropbox/pankraz/SAPL$ ls -l startjava.sh
-rwxr-xr-x 1 robert robert 574 Jan 20 00:27 startjava.sh
robert at chrissy:~/Dropbox/pankraz/SAPL$ ./startjava.sh
-bash: ./startjava.sh: Permission denied


executing the same script using sh:

sh ./startjava.sh

works fine.

What could be the reason?

thanks for your help

Robert