Alert: ASCOM broken by windows update!


Bob Denny has also now tested the TSX issue and is aware of it. As you said, it is now clear that it is not just the DCOM in this particular case. He has posted his findings to the SB site. Hopefully that will encourage them to do something to fix it. Here is a link to his post:

Bob Denny Post to SB forum


I’ve just installed the latest win10 update. Most things appear to be working. However, my CGXL mount will no longer connect to POTH (I use POTH to integrate the mount and the dome). In attempting Scope Connection, Choose Scope in POTH I get an error popup in ASCOM Chooser saying "Failed to load driver …etc."
My dome driver still connects to POTH and I can connect to the mount directly to SGP, but I am not sure how to link the dome and the mount other than via POTH. I guess I will have to un-install the Win10 update for now.


Last night we had Windows install that update again anyway despite having checked “defer updates”!

Another way to maybe help keep installs from happening is to set installs not to run during active hours (I am sure all of us already have that set to night imaging hours) and then shut the PC down during the daytime 'inactive" hours. It can’t install if the PC is off!

Hopefully MS would honor that, they did not seem to honor the defer.

We are getting very close to just nuking W 10 and reinstalling 7 on all astro-imaging machines.


Further to my post above, I set up dome control in SGP and it works a dream, slaving as required so I no longer need to use POTH to link the mount and the dome. Not sure why I used POTH in the first place.


If you are running Windows 10 Pro you can permanently disable automatic updates to give yourself as much time as needed to get updated ASCOM drivers. Using the Group Policy Editor, you can select an option to turn off automatic updates and make updates only install when you request it. It seems unlikely to me that there will be any Windows 10 updates in the next year (or ever) that an observatory PC must have. I don’t use TSX but I have backed out the problem update and everything works properly.

To see how to use Group Policy Editor to make this change:

In this update, you want option 2.

NOTE: I don’t think Group Policy Editor is available in Windows 10 Home.



I am not certain of this as it was more than 6 months ago, but I recall doing this and setting it to “download and ask before installing” (like W7 used to be) and it did not work.


On my main imaging PC, I have done just that. I am not aware of anything that requires Windows 10 and as this is dedicated for astro, is not exposed to email, browsing etc.
Thankfully my NUC still has drivers for Win 7 - but my Intel Stick does not :frowning:
One thing that it does bring to the fore - with the SB software, all the settings are in the documents folders which is easily backed up, the SGP settings are in hidden directories and can be overlooked…


By way of an info/update, I reported earlier that installing KB4056892 resulted in my CGXL no longer connecting to POTH (which I use to integrate mount and dome for slaving). Rather than un-installing the win10 update I tried connecting my CGXL directly to SGP (success) and using SGP’s Observatory facility and all appeared to work, though slaving accuracy was a little bit off, (this might be fixable by tweaking the dome geometry settings). However, I then discovered that when using ‘Centre Now’ on targets where the mount counterweight bar was almost horizontal (and the dome aperture is at its greatest offset from the mount azimuth), the dome would hurtle off some 10 or 15 degrees resulting in a first plate-solve image of the inside of the dome. I found this problem decreased the nearer the dome slot was to the mount azimuth. The dome log shows it is going where it is told to go, so something may be not quite right in the way SGP is calculating the dome position for a centre now process (though it seems to get the sums right for a Slew Now).

Since I have had no problems with my previous POTH setup I tried Bob Denny’s work-around and changed the Authentication Level from None to Call in the ‘ASCOM multi-interface server for Celestron Mounts’ in Component Services, DCOM Config, and that resulted in my CGXL once again connecting to POTH. A few trial runs and everything appears to be working as before. I plan to leave things like this unless anybody suggests otherwise.


The easiest way to prevent new MS updates from being installed for as long as you wish, is to change your network connection to a “metered” connection. MS never downloads updates on a “metered” connection because it is assumed to be either very slow, or very costly, such as a cell phone. This change would be permanent, so long as you keep it a “metered” connection. Detail here:

This works on all version of Windows 10, including Home.


Yes, I knew about that and we will probably do that if they force updates anyway or we run out of time with no fix in the TSX mount driver. Of course I suppose they could override that as well if they wanted to. They may already at their discretion. Here is what one source (Tenforums) had to say:

Windows will automatically download and install updates, except on metered connections. In that case, Windows will automatically download only those updates required to keep Windows running smoothly.

So does MS think this update is required to keep Windows running smoothly? Who knows?

I have also seen some suggestions that one could block access to the Windows update servers at the level of your router. If that worked it would be immune from being bypassed by MS.


Before we all feel comfortable with the widely reported ‘metered’ idea, it apprarently only works with WiFi connections. It does not affect LAN ones. In the latest version of Windows, I couldn’t find the ‘metered’ option any more (the horse has bolted anyway). Was is removed with the latest cumulative update?
I have since moved back to Win 7 and found a utility ‘never 10’ that looks promising, for changing some registry values to prevent the update process from loading at start. I’m looking into it.


Thanks Buzz. Keep us updated on the W7 thing. I have read in a couple places (I no longer remember where, I have read so much on this issue!) that this kind of update may eventually show up in W7 as well. Not sure how accurate that is.

What we really need is a fix of the driver (and maybe TSX?) from SB so that it works with the updated 10. Maybe Microsoft will release an “updated update” as well, who knows?


Can’t say for TSX issues other than connectivity, but for the time being the ASCOM Initiative is recommending that driver authors not make changes just yet. The update info from Microsoft says that this is a “known issue” and that it will be “resolved” in the future. Whether it was accidental or on purpose is unclear. There is a non-zero chance that making a “permanent” change to drivers will be unnecessary at a minimum, and possibly create other problems.


I had issues but just reinstalled all my drivers etc and everything works fine PhD,focused, etc


It might be early days and I have not had a clear night to run the system in anger but I loaded the full suite of applications from scratch and everything appears to connect and operate in Win7 ( ASCOM/TSX/SGP/BYE/C2A/Nebulosity/PHD2/CCDInspector/AstroPlanner etc). When I installed the OS, I checked the installed updates - nothing as late as KB405689X which came out this year for Win7. I allowed it to update itself for an hour and then disabled further ones, removing the pending ones in the windows download folder. This is a standalone PC and is not used for browsing or email, so unless someone gets through my hardware firewall…
The reason I upgraded from Win 7 to Win 10 was that its Microsoft Remote Desktop allowed multiple monitors. As soon as I can I will continue my sequence and confirm full operation. If it all works, I will probably stick with Win7 until hardware or software compatability issues force me to change.


At work, where we made microanalysis systems, we would supply a PC as part of the system. We would buy them in batches, enough for six months, and would test with that particular version of software and hardware. We would disable updates. We would discourage running additional software.

Expecting multiple pieces of software to run together on a variety of hardware and software platforms is a big ask. When you put everything together I wonder if any two systems are identical.


[Update] – I loaded Win7 Pro to replace my troubled Win10 Pro installation but retained all the SB files in my User’s document folder. PHD2 and TSX were able to calibrate the guider using DirectGuide and I assume my issues with DirectGuide relate to the security update that caused all the hilarity.
@Ken - could you consider putting SGP profile and setup files in a user documents folder too for the future? It is more likely to be picked up by backup programs :wink:


The following article documents 7 ways of disabling, to one degree or another, windows 10 updates.
Method #7 appears to be, by far, the best, assuming you want to disable them permanently.
It is: Method #7: Disable Windows Update Service
Very simple to implement, requiring only a few mouse clicks, works for all versions of windows 10. Totally disables windows updates forever.
I have not done this myself, having disabled them for 35 days. If other better fixes don’t show up by then, this is my go to solution.


The ASCOM people have provided a tool that automates the process of changing the DCOM security for ASCOM components.
It’s available from the ASCOM Initiative site:
Instructions and background information is available from there.


Chris - do you happen to know if this is a one-time thing, or would one have to do it after subsequent Microsoft updates. Another thing occurs; if an affected application is updated, without their developers changing its dependence, would that cause the user to run this utility again too?