If you encounter this issue of the below error during PO Creation, you need to input PBXX and then fill the Price which is a work around.
But, you can find the root cause of the issue to fix the issue completely.
Go to M/06 or SPRO-IMG Reference-Material Management-Purchasing-Conditions-Define Price Determination Process-Define Condition Types and verify whether any one assigned Access sequence wrongly. If yes, you can remove and save.
Once you move the configuration TR to your testing client or quality client, you can test which will work fine
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