I am trying to reverse a document 1001637 in EA21 but getting the following error
Document 1001637 cannot be reversed for adjustment due to document 1001636
Message no. AH758
Document 1001637 is to undergo a special reversal. Document 1001637 already represents the new billing of document 1001636, which was reversed for adjustment. It is not possible to link adjustment reversals by means of a renewed adjustment reversal.
A normal reversal must be executed for document 1001637 - that is, an invoicing and billing reversal. If this is no longer possible, you can create a manual credit memo or backbilling.
In table ERCH the document 1001636 is being shown as reversed.
Can somebody explain me what this error message means?
The F1 help of the error that you have posted explains the root cause error quite substantially.
As per Standard SAP, you cannot perform an adjustment reversal of a document (1001637) which has been created against another adjustment reversal (1001636).
In table ERCH, the previous document 1001636 should show as reversed because document 1001637 has already replaced it in SAP.
Follow the procedure as stated in help to fix the issue.
Hope it helps...