I have a custom field (type- Text(18) (External ID)) say Ext_ID__c on a custom object. We are using custom profile assigned to a group of users. For few users, Ext_ID__c is accessible, however for few users, this Ext_ID__c is not accessible. I checked the accessibility on User ID and its related Ext_ID__c through UserRecordAccess object.
We are using angular to display UI and Salesforce is being used to maintain database. We are using FeedItem to post chats and the Ext_ID__c is somehow related to the posts. When the users (who does not have access to Ext_ID__c) try to post anything, the data does not get saved on FeedItem and we get the error "INVALID_CROSS_REFERENCE_KEY".
Please suggest what could be the possible cause and how can we resolve this.