Message type: E = Error
Message class:  FI - TR-FM Funds Management 
Message number: 308
Message text: Select at least one top commitment item
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 FI308 ("Select at least one top commitment item") typically occurs in the context of financial transactions, particularly when dealing with commitment items in the Public Sector Management (PSM) module or when working with budgetary control.
Cause:
This error message indicates that the system requires at least one top commitment item to be selected for the transaction you are trying to execute. Commitment items are used in budgetary control to categorize and manage budget allocations and expenditures. If no top commitment item is selected, the system cannot proceed with the transaction because it lacks the necessary information to determine where the funds should be allocated.
Solution:
To resolve the FI308 error, follow these steps:
Select a Top Commitment Item: 
When you are in the transaction screen, look for the section where you can select commitment items. Ensure that you select at least one top commitment item from the available list.
Check Configuration: 
If Get instant SAP help. Sign up for our Free Essentials Plan.
Get instant SAP help. Sign up for our Free Essentials Plan. 
FI307 Commitment item &/& has a higher level item
What causes this issue?  The system issues an error message and will not allow you to continue with this transaction until the error is resolved. Syst...
FI306 No commitment item assigned to G/L account &/&, or assignment not valid
What causes this issue?  The system issues an error message and will not allow you to continue with this transaction until the error is resolved. Syst...
FI309 Object has no successor
Self-Explanatory Message Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of...
FI310 Incorrect financial transaction or item category in item & &
What causes this issue?  As cash budget management is active in this company code, you must enter a commitment item.System Response  The system issues...
Click on this link to search all SAP messages.