Hello, Magisian.
Thank you for your reply. These are the results of your suggestions.
1. Can you go to Portal for ArcGIS > Content > Add Item > Feature Layer?
- We tried adding an item in the Portal and it resulted an error below.
2. Can you publish a layer from ArcGIS Pro?
- Yes. No error when publishing in ArcGIS Pro.
We also tried some of the workaround in the link you provided. However, we still get the same error.
Thank you for your suggestions on this matter.