"path cannot be empty" error when exporting report to PDF format

Issue:

For certain reports that was created in TIBCO Jaspersoft® Studio and published to the TIBCO JasperReports® Server, there is a failure when exporting to PDF format.

The error that is displayed on the browser page is:

There was an error on the server. Try again or contact site administrators. (Error UID: 7f214198-72c8-46e0-9fbf-85042cd192f9)

and the jasperserver.log file captures the error "java.lang.IllegalArgumentException: path cannot be empty" :

2021-08-06T07:05:26,901 ERROR SecureExceptionHandlerImpl,https-jsse-nio-443-exec-9:116 - There was an error on the server. Try again or contact site administrators. (Error UID: 7f214198-72c8-46e0-9fbf-85042cd192f9)
2021-08-06T07:05:26,902 ERROR ErrorPageHandlerAction,https-jsse-nio-443-exec-9:118 - Error UID 7f214198-72c8-46e0-9fbf-85042cd192f9 java.lang.IllegalArgumentException: path cannot be empty
    at com.jaspersoft.jasperserver.api.metadata.common.service.impl.hibernate.util.RepositoryUtils.resolveRelativePath(RepositoryUtils.java:138)
    at com.jaspersoft.jasperserver.api.engine.jasperreports.util.RepoRepositoryService.getInputStream(RepoRepositoryService.java:112)
    at net.sf.jasperreports.repo.StreamRepositoryService.getInputStream(StreamRepositoryService.java:43)
    at net.sf.jasperreports.repo.InputStreamPersistenceService.load(InputStreamPersistenceService.java:51)
    at net.sf.jasperreports.repo.InputStreamPersistenceService.load(InputStreamPersistenceService.java:41)
    at com.jaspersoft.jasperserver.api.engine.jasperreports.util.RepoRepositoryService.getResource(RepoRepositoryService.java:182)
    at net.sf.jasperreports.repo.RepositoryService.getResource(RepositoryService.java:50)
    at net.sf.jasperreports.repo.RepositoryUtil.findInputStream(RepositoryUtil.java:195)
    at net.sf.jasperreports.repo.RepositoryUtil.getBytesFromLocation(RepositoryUtil.java:211)
    at net.sf.jasperreports.engine.export.JRPdfExporter.getFont(JRPdfExporter.java:2749)

Exporting the report/s to any other format works fine.

Solution:

The cause of the issue is a reference to a PDF Font that is invalid. 

In TIBCO Jaspersoft® Studio, navigate to the Source tab and search for any invalid entries relating to pdfFontName attribute.

For example, the main report or subreport contains a style tag that has an empty reference to pdfFontName like this:

<style mode="Opaque" forecolor="#FFFFFF" backcolor="#B42314" pdfFontName="">

which is causing the "path cannot be empty"  error.

Remove this invalid entry and publish the report to the TIBCO JasperReports® Server before attempting an export of the report to PDF format.