Windows Core Dump Files Not Being Archived in Evergreen

Problem

When MongoDB crashes on Windows during CI test runs, the resulting minidump files (.mdmp) are not being uploaded to S3, preventing developers from debugging the crashes.

How It Was Discovered

During test execution on Windows, we observed that:

1. MongoDB crashes and generates .mdmp files successfully
2. The gather_mongo_coredumps.sh script runs and creates symlinks to the dump files
3. However, fast_archive.py reports "No files found for the input, exiting early"
4. The minidump files are never compressed or uploaded to S3
5. Developers cannot access crash dumps to debug the failures

Impact

• Windows crash dumps are lost and unavailable for debugging
• Increases time to diagnose and fix crashes on Windows
• Only affects Windows CI builds; Linux/Mac work correctly

Root Cause

Python on Windows cannot recognize Cygwin symlinks, causing file detection to fail in the archival script.