Message type: E = Error
Message class:  HRPADRUREPORTS - HR-RU: message class for HR RU reports 
Message number: 421
Message text: Vacation can not be extended. Another absence exists after the illness
Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of messages in the SAP system have a message text, however this is frequently insufficient to comprehend or resolve the problem.
To make things easier, more detailed information is frequently added to describe the issue, how to fix it, and the necessary steps or configuration modifications.
Unfortunately, there isn't any extra information in this error notice.
First, use our AnswerBot below to get a possible cause and solution (requires a premium subscription).
Also, review the in-depth Common Questions & Answers listed below; you could discover a solution there or be able to connect with others who have faced similar challenges.
You can also try searching the SAP support portal (support.sap.com) but you need a special user ID to access it. It is possible that an SAP support note exists that provides additional details about the mistake or even steps for fixing it.
The SAP error message HRPADRUREPORTS421, which states "Vacation cannot be extended. Another absence exists after the illness," typically occurs in the context of managing employee absences in the SAP Human Capital Management (HCM) module. This error indicates that there is a conflict in the absence records for an employee, specifically when trying to extend a vacation period.
Cause: Existing Absence Record: The primary cause of this error is that there is an existing absence (such as sick leave) that overlaps with the vacation period you are trying to extend. SAP does not allow vacation to be extended if there is another absence that follows it. Absence Type Configuration: The configuration of absence types in SAP may also restrict the ability to extend vacation if certain conditions are not met. Incorrect Date Entry: There may be an error in the dates entered for the vacation or the illness, leading to an overlap that SAP recognizes
 Get instant SAP help. Sign up for our Free Essentials Plan.
Get instant SAP help. Sign up for our Free Essentials Plan. 
HRPADRUREPORTS420 * Illness during vacations (IDV)
Self-Explanatory Message Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of...
HRPADRUREPORTS407 Insurance Certificate data already modified
Self-Explanatory Message Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of...
HRPADRUREPORTS422 Not enough quota in the current period for the vacation extension
Self-Explanatory Message Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of...
HRPADRUREPORTS450 No one infotype &1 with subtype (&2) was found
Self-Explanatory Message Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of...
Click on this link to search all SAP messages.