Message type: E = Error
Message class:  HRPSGB_HER - HR PS GB Higher Education Messages (USS, HESA etc) 
Message number: 300
Message text: Previous emp. Institution code must exist if previous employment = '01'
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 HRPSGB_HER300 indicates that there is an issue with the previous employment data being entered in the system. Specifically, the error states that if the previous employment type is set to '01' (which typically indicates that the employee has previous employment), then the corresponding institution code for that previous employment must be provided and must exist in the system.
Cause: Missing Institution Code: The most common cause of this error is that the institution code for the previous employment is either missing or not entered in the system. Invalid Institution Code: The institution code entered may not exist in the database, meaning it has not been defined or is incorrect. Incorrect Employment Type: The employment type may not be set correctly, leading to the system expecting an institution code when it shouldn't.
Solution: Check Previous Employment Data: Review the employee's previous employment data in the system. Ensure that the employment type is set
 Get instant SAP help. Sign up for our Free Essentials Plan.
Get instant SAP help. Sign up for our Free Essentials Plan. 
HRPSGB_HER299 HESA Record Validation Check Person.ACTCHQUAL.1 failed
 The system issues an error message and will not allow you to continue with this transaction until the error is resolved. Procedure for System Adminis...
HRPSGB_HER298 HESA Record Validation Check Person.ABLWELSH.2 failed
What causes this issue?  Person.ABLWELSH (Ability to teach through the medium of Welsh) must exist for providers in Wales where any (Contract.ACEMPFUN...
HRPSGB_HER301 Previous emp.Inst.code must NOT exist if prev empl not equal to 01 or 21
Self-Explanatory Message Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of...
HRPSGB_HER302 Previous employement institution code cannot be the same as the actual.
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.