Hi, Thank you for your job post.
I'm a web developer with over 8 years of experience in developing web frontend and backend.
I'm very familiar with PHP, Java and MySQL, also I have rich experience in mobile app development.
I can fix the issue successfully and perfectly.
Questions :
1. I think this error comes from backend api. could you share the backend source code with me?
2. Do you need to fix the frontend too?
3. From skills required, do you need to develop mobile app?
I'd like to discuss in more detail
Regards.