Hello Poulami,
Looking at the IDoc content, it seems that there is a batch session generated through BDC programming with the header content(ZIS_IDOC_FIN_HDR segment of IDoc) and the item content(ZIS_IDOC_FIN_INFO segment of IDoc). This entire flow is related to FI process. The header contents can be checked in APQI table and item contents can be checked in APQD table. However, AFAIK, APQI table does not contain all the fields that are there in header content of the IDoc. Same is the case with item content. As a result of which depending on the end to end flow in the complete business process this error might be occurring where the IDoc could not possibly be parsed at the initial header level.
So, I suggest you to please check the functional flow as well in order to understand the reason for this error.
Also, you can check the date format as Amit suggested.
Kind Regards,
Souvik