The setup:
1. Org contains a custom object called objectX__c
2. A packaged app also contains a custom object called objectX__c but Salesforce automatically added a namespace there i.e. `someapp__.objectX__c`
3. The org has a custom lookup field on the account that looks to objectX__c, i.e. `Account.lookup_objectX__c`
4. The package app tries to run a query as `select id, lookup_objectX__r.some_field__c from Account`
5. This error occurs 

No such column 'some_field__c' on entity 'someapp__objectX__c'. If you are attempting to use a custom field, be sure to append the '__c' after the custom field name. Please reference your WSDL or the describe call for the appropriate names.

This error should not be happening because the lookup field is setup correctly to look at the non-namespaced object, but Salesforce is looking at the namespaced object which then fail.

The setup:
1. Org contains a custom object called objectX__c
2. A packaged app also contains a custom object called objectX__c but Salesforce automatically added a namespace there i.e. `someapp__.objectX__c`
3. The org has a custom lookup field on the account that looks to objectX__c, i.e. `Account.lookup_objectX__c`
4. The package app tries to run a query as `select id, lookup_objectX__r.some_field__c from Account`
5. This error occurs 

No such column 'some_field__c' on entity 'someapp__objectX__c'. If you are attempting to use a custom field, be sure to append the '__c' after the custom field name. Please reference your WSDL or the describe call for the appropriate names.

This error should not be happening because the lookup field is setup correctly to look at the non-namespaced object, but Salesforce is looking at the namespaced object which then fail.

The setup:
1. Org contains a custom object called objectX__c
2. A packaged app also contains a custom object called objectX__c but Salesforce automatically added a namespace there i.e. `someapp__.objectX__c`
3. The org has a custom lookup field on the account that looks to objectX__c, i.e. `Account.lookup_objectX__c`
4. The package app tries to run a query as `select id, lookup_objectX__r.some_field__c from Account`
5. This error occurs 

No such column 'some_field__c' on entity 'someapp__objectX__c'. If you are attempting to use a custom field, be sure to append the '__c' after the custom field name. Please reference your WSDL or the describe call for the appropriate names.

This error should not be happening because the lookup field is setup correctly to look at the non-namespaced object, but Salesforce is looking at the namespaced object which then fail.