I have run into a situation when tried to migrate reports from JasperReports Server (JS) 4.5 to JS 5.5. All reports work fine in JS 4.5 without any problem.
However, when JS 5.5 is installed on a different server and import reports from JS 4.5. We encountered fonts problem when reports are exported to pdf. The error message is enclosed in the screen cap.
Note: All reports are working fine in iReport 5.5.1 and JS 4.5.