Why do big companies run old software versions?
You might work in a big company or used equipment such as ATM from a big company, then notice the software is a few years old and wonder why it's not the latest version
At home, most people let their devices follow the update sequence defined by the manufacturer and the devices are updated in that order. Then when buying a new device, it's often the latest or the second latest version already applied
Then when you look at big companies. Even if they bought the latest computer, coming with the latest and greates withing software. They'll often downgrade the software to a version that's quickly 2-5 years old
Stability/Security VS Features
The first thing one need to understand, is that there exist two main types of updates
Feature update
As the name might reveal, feature updates are when new features are added to an software. Such as adding a search feature or redesigning how the software looks
Stability and security update
The other kind of update avoid as much as possible changing how the software works, but focuses on the software being secure against attacks and providing bug fixes, to ensure the software work as intended
As you might have already realized, one of the reason big companies run on older software is to ensure stability and security
Latest software can often comes with bugs or stability issues, which can interup work. At home, this is often not an issue. When you look at a company, every minute cost money if people can't work and even worse, can result in the company getting hacked
Running older version of a software, doesn't mean it's not getting security updates. Software companies often offer business software versions with extended security and bug fixes
Where the home version might get 2-3 years of updates, before the next version have completely replaced it and no more updates is provides. Business software often get 5-10 years of security and bug fix updates
Cost
Another asspect is the cost related to upgrade. Big companies need to make sure new software is compatible with other software and hardware they're using, or they'll also needs to upgraded or risk applications stop working
After it's decided to upgrade, it can take a year or two for project to test and prepare everything in bigger projects. Especially if the company doesn't use vanilla off the shelf software, but instead running inhouse or customized software
Big companies often run lots of different software that needs to communicate with each other and downtime can cost millions. So it's important that everything is tested to ensure it functions before the update is applied
This is why big companies normally have one or more test systems, that are near identical to the production system. Where they can apply and test updates, before applying them into production
Legacy software
Lastly you have legacy software, that often can be found in critical infrastructures. Legacy software is old software, often written in an programming language no longer commonly used. Where few to none have knowledge on how it works. This is software that can be very hard to upgrade or make adjustments to
These software sometimes perform so specific tasks and is so hard to upgrade, that some companies at one point straight out forced to create new software, to replace it
This can be very costly and is also why some companies rather pay to get extended support or run it unsupported, to delay upgrading as long as possible
Lawyers
Banks, governments and casinos for example, often have a lot of legal requirements before being able to update software
I had an old colleague who used to work within the casino industry, as a software developer. He said the pay was great, but the work was so restricted. Most software was legacy software and making adjusted took so long time. As every change needed to be approved by lawyers, to ensure everything was compliant with the law (normally the grey area of the law)
On the other end, you have governments areas such as police, who handles a lot of highly classified information. Where not everyone is legally allowed to even work on their software. Here the laws can require the person working on the software being a citizen of the country, located within the country, pass high level screening records and sometimes even be police themselves
Bureaucracy
Big companies often also suffer from heavy bureaucracy. Something small and simple can take a long time to complete, as it's such a big and time consuming process to get it approved
Home user VS Big Company
As you see, upgrading software is often not as easy as just applying the latest update when it comes to big companies
Home users and smaller companies, often just run latest software and updates as new updates get automatically applied
When running out of the box software and often less legal requirements, it's often good enough. Big companies wishes they could so the same, but with aspects such aslegal requirements and cost of interruption in mind, it's often to risky to just update to latest version for an big company
