How To Fix O1026 - First sched.date does not match fact.day "from day" &, check

O1026 - Overview

• Message type: E = Error

• Message class: O1 - IS-Oil : Message pool exchanges

• Message number: 026

• Message text: First sched.date does not match fact.day "from day" &, check

What causes this issue?

"Valid from" date in quantity schedule does not match the first
schedule line in the quantity schedule.
&SYSTEM_RESPONSE& / &SYSTEM_MESSAGE&
This message is controlled by Table T160M (System Messages).
If it is defined as "W" (Warning), you get a warning message; if it is
defined as an error, you get an error message (default W). If the
message occurs while processing a contract, the system is not able to
check and update the relevant contract scheduling line with a requested
<DS:GLOS.delivery date>delivery date</> delivery date, which is before
the date of the 1st scheduling (-> see message O1094 ). Within the
call-off, the system is not able to check the goods receipt/delivery
against the call-off schedule line, the update of a
<DS:GLOS.goods receipt>GR</>/<DS:GLOS.delivery>delivery</> occurs
in the last schedule line of the related
<DS:GLOS.release order>call-off</>.
The reason that the message appears may be that after creating the
(quantity schedule), the validity period changed or a schedule line was
manually deleted.

How to fix this error?

Check the validity period in the quantity schedule.
Check the first scheduling date of the schedule lines.
If a warning appears and you insert a new scheduling period, please use
a valid function key (e.G. Select all, Deselect all...) with a POPUP,
press cancel on the popup-screen or call QS again after leaving.
Insert a new scheduling line (period) with the first
<DS:GLOS.factory_calendar>factory</> day after "valid from" date
<ZH>or</> use function "Restructure QS".
&DEPENDENCIES&
<DS:DE.OIA_ENTLU>Breakdown indicator</> and <DS:DE.VONDAT>valid from
date</>

Error message extract from SAP system. Copyright SAP SE.

Smart SAP Assistant

• What is the cause and solution for SAP error message O1026 - First sched.date does not match fact.day "from day" &, check ?

  The SAP error message O1026, which states "First sched.date does not match fact.day 'from day' &, check," typically occurs in the context of scheduling or planning within SAP, particularly in modules related to production planning or project management. This error indicates a mismatch between the scheduled date and the actual date (fact day) that is expected in the system.
  
  Cause:
  
  
  Date Mismatch: The primary cause of this error is that the first scheduled date for a task or operation does not align with the actual date that the system is trying to reference. This can happen if:
  
  The scheduling parameters have been incorrectly set.
  There are changes in the project timeline that have not been updated in the system.
  The data entry for the scheduled dates is incorrect.
  
  
  
  
  Configuration Issues: There may be configuration issues in the scheduling settings or in the master data that define how dates are calculated and displayed.
  
  
  Data Integrity Issues: If there