The topics @chris suggested are to help the community help you. In order to understand your issue and provide advice, we need to know where you are, how you got there, and what you’ve tried. Up front clarity around these details will reduce some of the back and forth that will otherwise add delay to understanding and potentially resolving an issue.
Courteous communication and respect for those who volunteer to help will always go a lot farther than venting frustration as a welcome post, so I hope future interactions are more positive.
Threads from 2014 (MongoDB 2.6) are also unlikely to be overly relevant for modern versions of MongoDB, as much has changed including the default storage engine.
Thanks for providing further details. Unfortunately “core dump” just means the process terminated unexpectedly and captured the current state of working memory. Context like MongoDB version, O/S version, and a stack trace or exception error are required to provide any guidance on why a core dump may have occurred. Running binaries on supported microarchitecture has an unfortunately vague outcome at the moment, but you should see
signal=ILL which means an illegal, unknown, or privileged instruction was attempted.
MongoDB 4.4 is the latest version with binary packages compatible with Raspberry Pi 4, but it is possible to build from source if you want to use MongoDB 5.0 features.
For related discussion please see Core dump on MongoDB 5.0 on RPi 4 - #14 by Stennie.