Symptoms: When you input the Appeon product key during installing Appeon Server on Ubuntu, you may get an error saying "The product key [XXXX] you specified is not valid" as shown below.
Cause: It is caused by the "-e" before every line. Appeon takes it as a part of the Appeon product key.
Solution: Remove "-e" before every line by using '. install.sh' or 'source install.sh' to run install.sh.