Downgrading MongoDB to version 4.4 on CentOS, AlmaLinux, and RockyLinux

MongoDB 5.0 and every later version need a CPU with AVX instructions. On an older processor, or a virtual machine whose CPU model hides AVX, mongod crashes at start with "Illegal instruction". The usual workaround is MongoDB 4.4, the last version without that requirement. This guide shows how to check, the risks of running 4.4 in 2026, and how to install it safely on your own AlmaLinux or Rocky Linux 8 server.

1. Confirm AVX is the problem

The symptoms are distinctive. sudo systemctl status mongod shows the service failed with status=4/ILL, and running mongod --version by hand prints Illegal instruction (core dumped).

Check the CPU flags:

grep -o -m1 -w avx /proc/cpuinfo || echo "No AVX on this CPU"

If avx is printed, AVX is present and the crash has another cause; see debugging and troubleshooting MongoDB. If it isn't, MongoDB 5.0 or later will not run here, whatever you configure.

On a virtual machine, the physical host may support AVX while the CPU model presented to your VM does not. Ask whoever runs the host.

2. Decide before you downgrade

The operating system matters too. CentOS Linux 8 reached end of life at the end of 2021 and CentOS Linux 7 in June 2024, so neither gets security updates. Use AlmaLinux or Rocky Linux instead. We checked MongoDB's repository on 23 September 2026: 4.4 packages exist for the RHEL 8 family (the latest was 4.4.31), and the RHEL 9 repository has no 4.4 packages. So on AlmaLinux or Rocky Linux 9, 4.4 can't be installed from MongoDB's repository. There, running MongoDB in a container is the usual route; see running MongoDB in a Docker container.

3. Why you can't just swap the binaries

MongoDB's own downgrade process requires you to lower the featureCompatibilityVersion while the newer version is still running, then replace the binaries, one major version at a time. Without AVX, the newer mongod can't start, so you can't do that step on this machine. Data files written by 5.0 or later will make 4.4 refuse to start.

The safe route is a logical export and import:

• If the data has only ever been used by 4.4 or older, keep the data directory as it is.
• If it was written by 5.0 or later, export it with mongodump on a machine that can run that version, or use an existing dump, then restore it into an empty 4.4 data directory.

Features that 4.4 doesn't have, such as time series collections, will not restore. Test the restore before you depend on it.

4. Install MongoDB 4.4 on AlmaLinux or Rocky Linux 8

The repository file, with the release number written out (on the RHEL 8 family $releasever also resolves to 8):

sudo tee /etc/yum.repos.d/mongodb-org-4.4.repo > /dev/null <<'EOF'
[mongodb-org-4.4]
name=MongoDB 4.4 Repository
baseurl=https://repo.mongodb.org/yum/redhat/8/mongodb-org/4.4/x86_64/
gpgcheck=1
enabled=1
gpgkey=https://pgp.mongodb.com/server-4.4.asc
EOF

Install, then lock the packages so a routine dnf update never pulls in a newer major version:

sudo dnf install -y mongodb-org
sudo dnf install -y python3-dnf-plugin-versionlock
sudo dnf versionlock add 'mongodb-org*'

For more on version locks, see how to version lock RPM packages.

5. Verify

mongod --version
mongo --quiet --eval 'db.version()'
sudo systemctl status mongod

The first two commands should report a 4.4 version. MongoDB 4.4 ships the legacy mongo shell; the newer mongosh also connects to 4.4 if you prefer it.

6. Lock it down

A 4.4 server gets no more security fixes, so reduce its exposure:

• keep net.bindIp: 127.0.0.1 in /etc/mongod.conf unless another server must connect, and then allow only that server's IP in your firewall;
• never open port 27017 to the whole internet;
• create an administrative user and set security.authorization: enabled;
• take regular mongodump backups and store them off the server.

7. Troubleshooting

• dnf still installs 6.0 or 7.0: another MongoDB repository is still enabled. Run dnf repolist | grep -i mongo, disable the others, then sudo dnf clean all. dnf --showduplicates list mongodb-org-server shows which versions each repository offers.
• Still "Illegal instruction": a 5.0+ binary is still installed. Check rpm -qa | grep -i mongodb.
• 4.4 won't start and the log mentions featureCompatibilityVersion or an unsupported data format: the data directory was written by a newer version. Start with an empty directory and restore from a dump.
• Permission or SELinux errors after moving the data path: the packages set up the default /var/lib/mongo. A custom path needs the right owner and SELinux context.

8. Running this on Domain India

MongoDB is server software, so on Domain India it belongs on a VPS. VPS plans are self-managed, with root access and no cPanel, so you install and maintain MongoDB yourself. Run the AVX check in section 1 on your VPS before you choose a MongoDB version; if AVX is missing, ask support about your options.

On shared hosting you can't run a MongoDB server, but a Node.js app can connect to an external managed MongoDB database. The App Platform runs Node.js apps with automatic detection, and other stacks with a Dockerfile. For choosing a database in the first place, see choosing between PostgreSQL, MySQL, SQLite and MongoDB. The card shows the live price, excluding 18% GST.

Ready to set up MongoDB on your own server? Compare VPS plans, or open a support ticket to ask about your options before you order.