This type of file is not allowed on your system
Message number SO322
Diagnosis
An attempt was made to create a document of a type not allowed by system administration.
System Response
The system does not accept documents of this type.
Procedure
Select another type.

Solution:
Just use the transaction code SOPE to add the postfix of the error report file

See SAP Notes 2184005
2184005 – Error message: Documents of this type are not allowed in your system (SO322) for attachments
Symptom
Error message: Documents of this type are not allowed in your system (SO322) displayed when creating attachment in GOS.
Environment
SAP Basis release independent
Reproducing the Issue

In any application transaction where GOS is available open the GOS Toolbox menuWith the service New -> Create Attachment add a new file

OR

In transaction SO01 or SBWP create a New MessageAdd a new attachment

Cause
The file type (extension) is not allowed in transaction SOPE
See Also
If the file type (extension) is allowed in SOPE, but the error message is still received check the Knowledge
Provider (KPro) errors in transaction SLG1 for the timeframe when the error occured. It’s possible to block
some file types and MIME-Types on content server side.
Consider the system customizing referring to KBA 1634908.
For specific Knowledge Provider (KPro) issues refer to KBAs:
1482012 – ContentServer: How to check the connection to content server
1800664 – Error: HTTP/1.1 401 Authorization Required SsfVerify failed: rc=5 when accessing a content repository
Keywords
SO 322, Dokumente dieses Typs sind in Ihrem System nicht erlaubt
Products
SAP NetWeaver Application Server for ABAP 7.1
SAP NetWeaver Application Server for ABAP 7.2
SAP NetWeaver Application Server for ABAP 7.4 for SAP Business Suite
SAP NetWeaver Application Server for ABAP 7.4, OEM version 1.0
SAP NetWeaver Application Server for ABAP 7.6 for SAP S/4HANA Cloud
SAP NetWeaver Application Server for ABAP 7.61 for SAP S/4HANA Cloud
SAP NetWeaver Application Server for ABAP 7.62 for SAP S/4HANA
SAP enhancement package 1 for SAP NetWeaver Application Server for ABAP 7.1