This happens if any languages that your Linux server environment does not support are used for names of Packages, Subsystems, Models or Diagrams inuploaded astah file. Please set any supported languages in Linux server environment to resolve this issue.
If you use a Ubuntu Linux, you can set it in /etc/sysconfig/i18n file, and then please re-upload the astah file.
i.e.) Setting supported languages in /etc/sysconfig/i18n file
Please refer to
How to install Astah Share on Linux
and make sure to have all required environment to use Astah Share.