[Koha] Error when adding an item

[Abda ANNE]

Hello,
I'm using Koha 3.04.03. I get the following error after an item to a
biblio record.

Can't call method "subfield" on an undefined value at
/Apps/koha-3.04.03/C4/Biblio.pm line 2835.

Could anyone help fix? I should mention that dispite the error, the
item is add to the record.

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Abda Anne
Bamako (Mali)