Waiting before upgrading

We all like a good upgrade, particularly when they are free. Having new features applied to a mobile phone or PC can often bring useful improvements to make using the device easier or more efficient.

Last Monday saw Apple release its latest desktop operating system, macOS 10.15 Catalina. Being a committed geek, I started the upgrade just 5 minutes after release.


For unknown reasons the upgrade failed and my home iMac would not start.  After some fault finding I found out the cause of the failure, the upgrade process had totally filled my hard drive. Despite having over 100Gb free before I started the 8Gb upgrade had wrecked my iMac.  Okay, not a problem, I follow the golden rule of data (have it in three places at once) and I have a good backup policy.  I formatted my iMac and started a restore.


The restore did not work. It failed after around 10% of my precious data was restored. Incidentally, at this point I started to keep a log of all my actions so far. A basic list of actions performed, in order, with a date stamp next to each one.  Keeping this kind of log can be vital when fault finding or when explaining the issue to technical support teams.

Thankfully my IT knowledge and understanding allowed me to find and resolve the underlying issue. (For those of you who may be interested, I had to delete a partially completed TimeMachine backup before I could start a second restore.)

Overall the process to perform a complete restore of my iMac took nearly four days.  That would be a disaster in any business.

Is there a better way?

I was reminded this week of advice from the NCSC on how to upgrade without breaking things.  The core of the advice is wait before starting an upgrade and test the upgrade on a small percentage of PCs before deploying to all.

I knew this advice. I knew this 20 years ago when I was working on Y2K projects. However, we have all become accustomed to having devices upgraded easily, promptly and without fuss that we tend to forget some long-standing advice.  The temptation of the new shiny tech overwhelms even the most experienced of us.

In general, this advice (to wait before upgrading) applies to major operating system or application updates. Security updates should be applied as soon as possible. However, testing the security update on one PC before applying it to the entire estate is advisable.


  • Have a good backup policy.
  • Perform a test restore from the backups to ensure the backup is viable.
  • Test a major operating system or application upgrade on one machine before deploying to all machines.
  • Wait, a short time, before upgrading to the latest and greatest major release. 

Have you had similar issues with upgrades? How did you recover?