Message type: E = Error
Message class:  OIJ_PRORATE - TSW: Message class for prorate calculation 
Message number: 031
Message text: Unit & is not a valid unit.
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 OIJ_PRORATE031, which states "Unit & is not a valid unit," typically occurs in the context of the SAP Oil and Gas (OIJ) module when there is an issue with the unit of measure (UoM) being used in a transaction or process. Here’s a breakdown of the potential causes, solutions, and related information for this error: Causes: Invalid Unit of Measure: The unit specified in the transaction does not exist in the system or is not defined correctly.
Configuration Issues: The unit of measure may not be properly configured in the relevant master data or in the customizing settings. Data Entry Errors: There may be a typographical error in the unit of measure entered by the user. Missing Unit in Master Data: The unit of measure may not be assigned to the material or product in the master data. Unit Conversion Issues: If there are conversion factors defined, they may not be set
 Get instant SAP help. Sign up for our Free Essentials Plan.
Get instant SAP help. Sign up for our Free Essentials Plan. 
OIJ_PRORATE030 Unit & is not convertible to unit &.
Self-Explanatory Message Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of...
OIJ_PRORATE021 No ticket exists yet for the pegged demand/supply item.
What causes this issue?  The item you selected is pegged with demand/supply pegging. However no ticket is posted yet for the pegged item.System Respon...
OIJ_PRORATE032 Demand material &1 is not equal to demand material &2
What causes this issue?  Items with different demand materials were pegged.System Response  The system issues an error message and will not allow you ...
OIJ_PRORATE033 Assigned quantity (&) is under the tolerance quantity (&).
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.