A 500 Internal Server Error typically occurs when an invalid or illegal character, such as symbols like ' " , : ; * ! @ # $ % ^ & * ( ), is entered into a field. These characters are not supported in certain fields and can disrupt the system's ability to process the data.
To avoid this error, ensure that only valid and acceptable characters are used when entering information. If the issue persists, review the input or consult support for further assistance.

For detailed information regarding valid and illegal characters, please refer to the article Valid Characters for Retail Express Fields