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Installing the ONE software

When you install the ONE software onto a Windows PC for the first time you will need to download the software from the Internet and this information will then be sent to you via email from our computer system. Once the software is running the program will automatically monitor for any updates and download it. Once it is ready for installation the Software Version information box on the ONE home page will display a message that it is ready and will offer an "Install Now" link - this link will not be enabled if a client session is running. Alternatively, if an update is ready to install then you will more specifically be notified by a message box the next time that you start the ONE software.

Once you click the Install Now link the ONE program will display an alternate page which shows that an update is underway. Depending upon the speed of your machine this may show and then disappear before you have finished reading the page. However, once the ONE software has terminated itself the update will be complete. Simply restart the ONE program to continue - please note that it might take a few more seconds than usual to load the first time after an update while the software finalizes a few update tasks.

Video Walkthrough:
Downloading, Installing, and Signing-in to the ONE System

​Below is a video which shows you how to download and install the ONE software, and how to log in to the system for the first time. However, if you don't feel the need to sit through the video then simple text instructions are shown below, together with some technical notes for troubleshooting any problems.

Text Instructions For Installation

This section is based upon the assumption that you have received an email from World Development Systems with instructions on how to download the software. In order to use the ONE program you need to have a subscription account created, and also an individual login account which is tied to the subscription - these are both automatically created when you when you sign up for a ONE system. The software is designed to be used by a single owner or by multi-users within the same subscription, such as a clinic.


So step 1 is to click the link in your email. You will initially be asked to sign in with some credentials, and you can quickly get to the download page from there.


Step 2 is to Open (or Run, depending on the browser you use) the file that has been downloaded. The installation program is built on a Microsoft technology called MSIX,  a new universal package format designed for Windows 10 & 11 apps that supports desktop, mobile, and other modern Windows devices. Windows 10 and 11 include direct support for MSIX. Therefore, all you need to do once the install program is running is click the Install button - this will just take a few seconds to copy the ONE files onto your computer. Once the install program has finished then it will disappear for a few seconds, but that's OK - it is still organizing files on your system and loading the program for the first time (which takes a bit longer). After a few seconds you will see the ONE program load, and it will ask you to sign in with the same credentials you used to download the software.

Creating a shortcut to the ONE program

When the ONE software is installed a shortcut is created under the All Apps section of the Start menu. Alternatively, you can click the Search icon and start typing the word One to find a list of all applications on your computer that begin with the letters One. However, if you use ONE regularly then it can be a bit of a chore hunting for the app every time. Fortunately you can very easily create a new shortcut on the main Windows desktop, or on the taskbar (which is the line of buttons along the very bottom of your screen). To do this simply click on the Windows Search icon if you have Windows 11, or the Search text box next to the Start button if you have Windows 10. In the search box type One System and you will see something like the window below for both variants of Windows. On the right side, shown here highlighted within a red box, you will see the options Pin to Start and Pin to Taskbar. If you Pin to Start then an icon will be created in the more visible section of the Start menu, but if you Pin to taskbar then a icon will be created along the bottom of the screen.


Troubleshooting Install Problems

Just because the Microsoft installer technology is shiny and new doesn't mean that it won't play up from time to time - hey, this is Microsoft after all! Sometimes - and it won't happen to you, only other people - but sometimes the install program will encounter some technical reason why it can't install and, to really help keep you centered and calm, will display some obscure error message talking about a "missing XML root node" or some such piece of obscurity. So if you see something like this then here are the tips that are most likely to get you running:


Restart Windows

Sometimes when Windows downloads its full monthly system updates it does a "partial" install, but the process will only be completed after a full restart. While in this partial state it will block other new programs from coming along and trying to install their own stuff, but the technology that the ONE installer is built on (which is a Microsoft component) is not very good at reporting that this is the reason and so it can give you weird and deeply unhelpful messages. Microsoft have promised to improve this but as of writing this has not happened yet.


Tip: Not trying to put you off here. If you do get any problems with updates then email us at because we are very experienced at dealing with it.


NB: Once the ONE system has been installed it will automatically check for any updates and download them automatically. If there are any Windows updates pending then it will tell you very clearly that you need to restart Windows.


NB2: Restarting Windows if different to performing a Shut Down. When you Shut Down Windows it actually hibernates itself, so many system files are kind of left open. This speeds up the start up process the next time that you switch your computer on, and in general this is a worthwhile speed benefit. However, a Restart fully shuts Windows down and then reloads everything from the beginning - at the start of which it checks to see whether there are any partial updates in progress and then it swaps the old files out for the new ones before fully loading the Windows operating system. To fully restart Windows you should go to the main Windows "Start" icon, click the power logo, and then choose Restart.


Restart Windows 10 (light mode by default)

Windows 11 Restart.png

Restart Windows 11 (dark mode by default)


Repair Windows - but contact us first if you are not sure!

OK, you're not going to like this. Sometimes, in our experience, Windows just becomes unstable over time as updates are applied and other programs get installed and do their own thing. If the ONE software simply refuses to install it will probably help resolve the problem if you restore Windows back to a pristine state. In years gone by this was a big deal but since Windows 10 came out Microsoft have made the process a great deal easier. 

However, if you have tried the Windows Restart option in item 1 (above) then we recommend that you contact us first by email, please see the support email address below.

Technical Support

For more information please see the main Technical Support page

Next step...

From here you should move onto the "Start Here" section 3,  Signing In

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