PKP PN export error for a single issue (OJS 3.4.0.9)

I’m experiencing an issue with the PKP Preservation Network (PKP PN). All issues from our journal have been successfully preserved except for one specific issue.

I have attempted to submit this issue several times, but the export always fails with the following message:

“Une erreur s’est produite pendant l’exportation d’un numéro. Consultez le fichier d’erreur (log) du serveur pour plus d’informations.”

Unfortunately, I do not have access to the server logs.

The journal appears to be correctly connected to the PKP PN, as the plugin reports:

Network Status: “The PKP PLN can accept deposits from this journal.”

In fact, the two most recent issues were successfully deposited and preserved. The problem seems to affect only this single issue.

Has anyone encountered this issue before? Is there any way to identify what might be preventing this particular issue from being exported, or any additional diagnostics I can perform without access to the server logs?

Thank you very much for your help.

Application: