external harddisk on ntfs format not mounting after 15.4.1 upgrade

IMDr wrote:

Yes, I was not writing. Only reading (copy the necessary files to Mac Book).

Uninstall the drive manufacturer's software.

When a third party NTFS driver is installed it takes over & becomes the default NTFS option. When that software is broken by an OS update, then that driver is broken & unable to function. Because that broken third party driver is the default NTFS driver now, you won't be able to access the external drive until that broken software is either updated or uninstalled.

macOS won't use the built-in NTFS read-only driver without manual intervention using the command line. Forget the command line as it is complicated & extremely risky to use since a simple typographical error could cause even more severe issues.

If you don't realize you have a third party manufacturer's drive software managing this drive or a third party NTFS driver, then run the third party app EtreCheck and post the complete report here so we can review it. If you are using such a third party driver, then the EtreCheck report will clearly show it. Or perhaps you have some other third party software that is interfering with the normal operation of macOS & affecting this external drive.

How to use the Add Text Feature When Posting an EtreCheck Report - Apple Community

Now that is stopped. Apple support told NTFS is not supported and to use, format the HDD and use, in that case all data will be lost. Apple suggested, take a backup in windows machine and after formatting copy the data back to HDD. While telling is easy, Apple don’t realise the time to copy and reverse copy.

Sometimes this is necessary and it is good advice. In fact I believe another contributor suggested the same thing here. Unfortunately this is necessary if a person misconfigures their system....sometimes this is the only solution & sometimes the fastest & easiest depending on circumstances.

It also concerns me that if the data on this drive is important, then why don't you already have a backup of this drive which would make the whole process even simpler since you would only need to copy the data in one direction instead of two directions?

You need to start backing up your whole computer and all external media (including the cloud) which contains important & unique data.

Also asked me to arrange my own since the file system is not supported. And I was not expecting such a pathetic response from Apple support. High recommendation not to buy Mac (Apple) since they seems to have a trade war with Win (MS) not supporting NTFS due to licensing cost and in future we may see other software compatibility issues too …

You are taking away the wrong message here. Apple does allow reading of NTFS volumes as long as other third party software such an a third party NTFS driver are not interfering with the normal operation of macOS.

It is the external drive manufacturer's who are to blame for your problem here because the majority of them will only format the drives as NTFS from the factory because they are focused on mainly supporting Windows users. Mac users are just an after thought with the supplying of the proprietary third party NTFS driver. Users need to understand their devices to know that using a native built-in file system is the best & most reliable option for external drives. With macOS those file systems are APFS, MacOS Extended (Journaled), and exFAT.....which one you choose depends on several factors such as the type of external drive (SSD vs Hard Drive) and how the drive will be used (data only drive, backup drive, or shared with an older Mac or Windows).

There are only a small number of companies which actually focus on Mac support with OWC being one of the best known & longest supporter of Macs. Some drive manufacturers are starting to format external drives as exFAT from the factory which eliminates the need for proprietary third party software to manage an external drive.

What is the make & model of this external drive?

What file system is used on this external drive?

Are you using the drive manufacturer's software at all? If so, then make sure that software is completely up to date. If it is up to date, then contact the drive manufacturer for assistance.

Within Disk Utility do you see the physical drive on the left pane? Within Disk Utility you may need to click "View" and select "Show All Devices" before the physical drives appear on the left pane of Disk Utility.

How is the drive connected to the Mac?

What cables, adapters, hubs, docks are being used with this drive?

What is the exact model of your Mac? You can get this information by clicking the Apple menu and selecting "About this Mac".

Try disconnecting all other external devices from the computer in case one of them is causing a problem. Connect the drive directly to the computer. Try using each of the USB ports on the computer. And try using another USB cable (make sure it is a good quality USB-C cable capable of at least USB3 data transfers). Not all USB-C cables can transfer data or do it well. These days there is a lot of junk cables & adapters out there. Even the cable the manufacturer's provide with the drive may not be of very good quality.

Edit: Just realized you did mention NTFS in the title of this thread. If so, then you must be using some third party NTFS driver software in order to be able to write to the NTFS volume since macOS only has read access by default. That software as @Barney-15E mentioned is most likely at fault. If you are not using this drive to share with a Windows system, then you should have erased it as APFS if it is an SSD, or as MacOS Extended (Journaled) if it is a Hard Drive.

And you should already have a backup of the data on this external drive if that data is important & unique, otherwise you will lose all those files if the drive fails or cannot be mounted.

I was using the hard disk but after upgrading sequoia os from 15.3 to 15.4.1, the hard disk is not mounting

The software you were using to write to the NTFS drive likely broke in the update. Contact the vendor for an update.

Do you need to connect that drive to a Windows computer? If not, move all the data, reformat as Mac OS Extended, then move the data back.

IMDr wrote:

I had not used any 3rd party software. It was Mac Finder, and desktop only

Then you would not have been able to write to the drive. If you were writing to the drive, then you had installed their software. When that software breaks, it can prevent even mounting the drive.

IMDr wrote:

I had not used any 3rd party software. It was Mac Finder, and desktop only

That’s impossible.

Either some add-on third-party NTFS app was installed, or the NTFS storage had read-only access. No write. Or the storage isn’t NTFS.

Maybe having Windows somewhere eventually is a problem for “eventually”.

If this storage volume is NTFS, off-load the contents temporarily, reformat the storage, and re-load it.

And you can set up a network File Share as an alternative to shoveling around hard disks, if “eventually“ ever arrives.