[GH-ISSUE #262] Freezes my entire system at every launch—with default preferences

gitea-mirror commented

2026-05-05 05:23:46 -06:00

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Originally created by @jackbrannen on GitHub (Jul 16, 2020).
Original GitHub issue: https://github.com/MonitorControl/MonitorControl/issues/262

Originally assigned to: @waydabber on GitHub.

Checklist

I have searched for existing issues
I have looked through the wiki
I have updated MonitorControl to the latest version

Describe the bug

Every time I launch MC with my external display plugged in, my system freezes (can't move mouse etc.). When I unplug my external display, my system unfreezes.

This persists even though I have trashed all pref files for MC, deleted the app, and redownloaded.

To Reproduce

Download MC and drag to Applications folder
Open
System freezes

Expected behavior

No freeze on launch

Additional context

The app was working with another MacBook Pro and the same display hardware and cable just a couple of days ago.

I am using default MC preferences. No modifications.

Environment Information (please complete the following information):

macOS version: 10.14.6
MonitorControl version: 2.0.0
Monitor(s): Dell P2715Q

Thanks!

Originally created by @jackbrannen on GitHub (Jul 16, 2020). Original GitHub issue: https://github.com/MonitorControl/MonitorControl/issues/262 Originally assigned to: @waydabber on GitHub. **Checklist**  - [x] I have searched for existing issues - [x] I have looked through [the wiki](https://github.com/MonitorControl/MonitorControl/wiki) - [x] I have updated MonitorControl to the latest version **Describe the bug** Every time I launch MC with my external display plugged in, my system freezes (can't move mouse etc.). When I unplug my external display, my system unfreezes. This persists even though I have trashed all pref files for MC, deleted the app, and redownloaded. **To Reproduce** 1. Download MC and drag to Applications folder 2. Open 3. System freezes **Expected behavior** No freeze on launch **Additional context** The app was working with another MacBook Pro and the same display hardware and cable just a couple of days ago. I am using default MC preferences. No modifications. **Environment Information (please complete the following information):** - macOS version: 10.14.6 - MonitorControl version: 2.0.0 - Monitor(s): Dell P2715Q Thanks!

gitea-mirror

2026-05-05 05:23:46 -06:00

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gitea-mirror commented

2026-05-05 05:23:53 -06:00

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@JoniVR commented on GitHub (Jul 16, 2020):

What setup do you have? (MacBook) do you happen to have an Nvidia GPU?

@JoniVR commented on GitHub (Jul 16, 2020): What setup do you have? (MacBook) do you happen to have an Nvidia GPU?

gitea-mirror commented

2026-05-05 05:23:55 -06:00

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@pkandarpa-cs commented on GitHub (Jul 16, 2020):

I also have this issue. Mouse moves with extreme lag when monitor control is running. My monitors are two P2719H

@pkandarpa-cs commented on GitHub (Jul 16, 2020): I also have this issue. Mouse moves with extreme lag when monitor control is running. My monitors are two P2719H

gitea-mirror commented

2026-05-05 05:23:59 -06:00

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@jackbrannen commented on GitHub (Jul 17, 2020):

MacBook Pro (Retina, 15-inch, Mid 2015)
Intel Iris Pro 1536 MB (not honestly sure if this is Nvidia)

On 16 Jul 2020, at 2:12, Joni Van Roost wrote:

What setup do you have? (MacBook) do you happen to have an Nvidia GPU?

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You are receiving this because you authored the thread.
Reply to this email directly or view it on GitHub:
https://github.com/MonitorControl/MonitorControl/issues/262#issuecomment-659182419

@jackbrannen commented on GitHub (Jul 17, 2020): MacBook Pro (Retina, 15-inch, Mid 2015) Intel Iris Pro 1536 MB (not honestly sure if this is Nvidia) On 16 Jul 2020, at 2:12, Joni Van Roost wrote: > What setup do you have? (MacBook) do you happen to have an Nvidia GPU? > > -- > You are receiving this because you authored the thread. > Reply to this email directly or view it on GitHub: > https://github.com/MonitorControl/MonitorControl/issues/262#issuecomment-659182419

gitea-mirror commented

2026-05-05 05:24:01 -06:00

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@JoniVR commented on GitHub (Sep 19, 2020):

I also have this issue. Mouse moves with extreme lag when monitor control is running. My monitors are two P2719H

This could be due to #49

MacBook Pro (Retina, 15-inch, Mid 2015)
Intel Iris Pro 1536 MB (not honestly sure if this is Nvidia)

Try going into Settings > Advanced and setting Polling Mode to None. Also, please post more details about the system it's not working on, specifically the GPU is probably important here.

@JoniVR commented on GitHub (Sep 19, 2020): > I also have this issue. Mouse moves with extreme lag when monitor control is running. My monitors are two P2719H This could be due to #49 > MacBook Pro (Retina, 15-inch, Mid 2015) Intel Iris Pro 1536 MB (not honestly sure if this is Nvidia) Try going into `Settings > Advanced` and setting `Polling Mode` to `None`. Also, please post more details about the system it's not working on, specifically the GPU is probably important here.

gitea-mirror commented

2026-05-05 05:24:04 -06:00

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@tierpinho commented on GitHub (Oct 12, 2020):

Same issue. On Mac, 10.15.7 👇 , with latest version of this software. Very bad bug.

Try going into Settings > Advanced and setting Polling Mode to None. Also, please post more details about the system it's not working on, specifically the GPU is probably important here.

Tried this, and awaiting some more testing...

@tierpinho commented on GitHub (Oct 12, 2020): Same issue. On Mac, 10.15.7 👇 , with latest version of this software. Very bad bug. ![Screen Shot 2020-10-12 at 08 26 19](https://user-images.githubusercontent.com/556908/95778850-a639c980-0c64-11eb-8c9a-71f5c458f35b.png) > Try going into Settings > Advanced and setting Polling Mode to None. Also, please post more details about the system it's not working on, specifically the GPU is probably important here. Tried this, and awaiting some more testing...

gitea-mirror commented

2026-05-05 05:24:07 -06:00

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@gjuchault commented on GitHub (Mar 26, 2021):

I also have this issue. Mouse moves with extreme lag when monitor control is running. My monitors are two P2719H

This could be due to #49

MacBook Pro (Retina, 15-inch, Mid 2015)
Intel Iris Pro 1536 MB (not honestly sure if this is Nvidia)

Try going into Settings > Advanced and setting Polling Mode to None. Also, please post more details about the system it's not working on, specifically the GPU is probably important here.

I have one monitor (Asus VG27A), same issue. Moving Polling Mode to None fixed it.

MacBook Pro (13-inch, 2019, Two Thunderbolt 3 ports)
1,4 GHz Quad-Core Intel Core i5
16 Go 2133 MHz LPDDR3
Intel Iris Plus Graphics 645 1536 Mo

@gjuchault commented on GitHub (Mar 26, 2021): > > I also have this issue. Mouse moves with extreme lag when monitor control is running. My monitors are two P2719H > > This could be due to #49 > > > MacBook Pro (Retina, 15-inch, Mid 2015) > > Intel Iris Pro 1536 MB (not honestly sure if this is Nvidia) > > Try going into `Settings > Advanced` and setting `Polling Mode` to `None`. Also, please post more details about the system it's not working on, specifically the GPU is probably important here. I have one monitor (Asus VG27A), same issue. Moving Polling Mode to None fixed it. ``` MacBook Pro (13-inch, 2019, Two Thunderbolt 3 ports) 1,4 GHz Quad-Core Intel Core i5 16 Go 2133 MHz LPDDR3 Intel Iris Plus Graphics 645 1536 Mo ```

gitea-mirror commented

2026-05-05 05:24:09 -06:00

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@waydabber commented on GitHub (Aug 21, 2021):

Please check if this issue still persists with the new 3.0.0 version. Thank you!

@waydabber commented on GitHub (Aug 21, 2021): Please check if this issue still persists with the new 3.0.0 version. Thank you!

gitea-mirror commented

2026-05-05 05:24:12 -06:00

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@jackbrannen commented on GitHub (Aug 21, 2021):

Yep, it insta-froze my system again. Could this be related to my running
SwitchResX? Third party app for custom screen resolutions.

On 21 Aug 2021, at 11:42, waydabber wrote:

Please check if this issue still persists with the new 3.0.0 version.
Thank you!

--
You are receiving this because you authored the thread.
Reply to this email directly or view it on GitHub:
https://github.com/MonitorControl/MonitorControl/issues/262#issuecomment-903134973

@jackbrannen commented on GitHub (Aug 21, 2021): Yep, it insta-froze my system again. Could this be related to my running SwitchResX? Third party app for custom screen resolutions. On 21 Aug 2021, at 11:42, waydabber wrote: > Please check if this issue still persists with the new 3.0.0 version. > Thank you! > > -- > You are receiving this because you authored the thread. > Reply to this email directly or view it on GitHub: > https://github.com/MonitorControl/MonitorControl/issues/262#issuecomment-903134973

gitea-mirror commented

2026-05-05 05:24:14 -06:00

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@waydabber commented on GitHub (Aug 21, 2021):

Huhh. Do you have DDC polling set to 'None'? This is the only thing that is DDC related and happens at launch time (but it should not cause a freeze).

If so then please try disabling 'Use hardware DDC control' to see if there is any change.

Also:

do you use a dock of any kind?
what happens if you try to read or change a DDC value using ddctl? Does that cause an instant freeze as well?

Thank you!

@waydabber commented on GitHub (Aug 21, 2021): Huhh. Do you have DDC polling set to 'None'? This is the only thing that is DDC related and happens at launch time (but it should not cause a freeze). If so then please try disabling 'Use hardware DDC control' to see if there is any change. <img width="803" alt="Screen Shot 2021-08-21 at 18 30 34" src="https://user-images.githubusercontent.com/37590873/130328595-89473295-e1f7-4627-ae8d-d3d5cd2a2581.png"> Also: - do you use a dock of any kind? - what happens if you try to read or change a DDC value using ddctl? Does that cause an instant freeze as well? Thank you!

gitea-mirror commented

2026-05-05 05:24:16 -06:00

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@jackbrannen commented on GitHub (Aug 21, 2021):

I’m not able to even get to this since my computer freezes instantly
when the app opens.

On 21 Aug 2021, at 12:32, waydabber wrote:

Huhh. Do you have DDC polling set to 'None'? This is the only thing
that is DDC related and happens at launch time (but it should not
cause a freeze).

If so then please try disabling 'Use hardware DDC control' to see if
there is any change.

Also:

do you use a dock of any kind?

what happens if you try to read or change a DDC value using ddctl?
Does that cause an instant freeze as well?

Thank you!

--
You are receiving this because you authored the thread.
Reply to this email directly or view it on GitHub:
https://github.com/MonitorControl/MonitorControl/issues/262#issuecomment-903141569

@jackbrannen commented on GitHub (Aug 21, 2021): I’m not able to even get to this since my computer freezes instantly when the app opens. On 21 Aug 2021, at 12:32, waydabber wrote: > Huhh. Do you have DDC polling set to 'None'? This is the only thing > that is DDC related and happens at launch time (but it should not > cause a freeze). > > If so then please try disabling 'Use hardware DDC control' to see if > there is any change. > > <img width="803" alt="Screen Shot 2021-08-21 at 18 30 34" > src="https://user-images.githubusercontent.com/37590873/130328595-89473295-e1f7-4627-ae8d-d3d5cd2a2581.png"> > > Also: > > - do you use a dock of any kind? > - what happens if you try to read or change a DDC value using ddctl? > Does that cause an instant freeze as well? > > Thank you! > > > -- > You are receiving this because you authored the thread. > Reply to this email directly or view it on GitHub: > https://github.com/MonitorControl/MonitorControl/issues/262#issuecomment-903141569

gitea-mirror commented

2026-05-05 05:24:18 -06:00

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@waydabber commented on GitHub (Aug 21, 2021):

Ohh, I see. We should probably add a "Safe mode" startup option that skips DDC checks if previously this caused issues.

Also, could you please give a little more detail on the following:

Does the app cause a freeze even if there is no external display connected?
What kind of connection/cabling do you use?
do you use a dock of any kind?
what happens if you try to read or change a DDC value using ddctl? Does that cause an instant freeze as well?

Also, can you send me the preferences file folder of your app me.guillaumeb.MonitorControl.plist? It is located under your user's Library folder (in Finder select the Go menu, press the Option key on the keyboard and then click on Library), where there is a Preferences folder. In this Preferences folder you should find this file.

Thank you!

@waydabber commented on GitHub (Aug 21, 2021): Ohh, I see. We should probably add a "Safe mode" startup option that skips DDC checks if previously this caused issues. Also, could you please give a little more detail on the following: - Does the app cause a freeze even if there is no external display connected? - What kind of connection/cabling do you use? - do you use a dock of any kind? - what happens if you try to read or change a [DDC value using ddctl](https://github.com/MonitorControl/MonitorControl/wiki/Monitor-Troubleshooting)? Does that cause an instant freeze as well? Also, can you send me the preferences file folder of your app `me.guillaumeb.MonitorControl.plist`? It is located under your user's Library folder (in Finder select the `Go` menu, press the `Option` key on the keyboard and then click on `Library`), where there is a `Preferences` folder. In this `Preferences` folder you should find this file. Thank you!

gitea-mirror commented

2026-05-05 05:24:19 -06:00

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@waydabber commented on GitHub (Aug 25, 2021):

Hi @jackbrannen please let me know if I can help you with this!

Btw, sorry for not responding to your question about SwitchResX. No, the two apps should not interfere with each other (I am a SwitchResX user myself).

@waydabber commented on GitHub (Aug 25, 2021): Hi @jackbrannen please let me know if I can help you with this! Btw, sorry for not responding to your question about SwitchResX. No, the two apps should not interfere with each other (I am a SwitchResX user myself).

gitea-mirror commented

2026-05-05 05:24:21 -06:00

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@jackbrannen commented on GitHub (Aug 26, 2021):

Thanks! May take me a while to get back to this.

On 25 Aug 2021, at 13:11, waydabber wrote:

Hi @jackbrannen please let me know if I can help you with this!

Btw, sorry for not responding to your question about SwitchResX. No,
the two apps should not interfere with each other (I am a SwitchResX
user myself).

--
You are receiving this because you were mentioned.
Reply to this email directly or view it on GitHub:
https://github.com/MonitorControl/MonitorControl/issues/262#issuecomment-905719325

@jackbrannen commented on GitHub (Aug 26, 2021): Thanks! May take me a while to get back to this. On 25 Aug 2021, at 13:11, waydabber wrote: > Hi @jackbrannen please let me know if I can help you with this! > > Btw, sorry for not responding to your question about SwitchResX. No, > the two apps should not interfere with each other (I am a SwitchResX > user myself). > > -- > You are receiving this because you were mentioned. > Reply to this email directly or view it on GitHub: > https://github.com/MonitorControl/MonitorControl/issues/262#issuecomment-905719325

gitea-mirror commented

2026-05-05 05:24:24 -06:00

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@waydabber commented on GitHub (Aug 31, 2021):

Hi,

Here is an unsigned test build. This requires you to click 'Open Anyway' in Preferences/Security. The source of this build is here - if you don't trust in unsigned builds and want to build it yourself.

With this version, if you press Shift during app startup, you'll see the following alert:

This will reset all preferences and also disable DDC read which probably causes the freeze. After this you can set Polling to 'None' in the Advanced section of Displays.

Can you please report back if this helps? Thank you!

@waydabber commented on GitHub (Aug 31, 2021): Hi, Here is an [unsigned test build](https://www.dropbox.com/s/w1md5rjyll0lsyo/MonitorControl.zip?dl=1). This requires you to click 'Open Anyway' in Preferences/Security. The source of this build [is here](https://github.com/MonitorControl/MonitorControl/tree/temp/debug) - if you don't trust in unsigned builds and want to build it yourself. With this version, if you press Shift during app startup, you'll see the following alert: <img width="372" alt="Screen Shot 2021-08-31 at 15 30 45" src="https://user-images.githubusercontent.com/37590873/131511392-44d195e6-0b79-4d39-b3bb-f6aeaf94192a.png"> This will reset all preferences and also disable DDC read which probably causes the freeze. After this you can set Polling to 'None' in the Advanced section of Displays. Can you please report back if this helps? Thank you!

gitea-mirror commented

2026-05-05 05:24:27 -06:00

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@jackbrannen commented on GitHub (Aug 31, 2021):

Hey @waydabber, you are so kind to offer all of this troubleshooting help. I started following your steps above and hit issues installing ddcctl. Truthfully this is more trouble that it's worth to me at this point—I hope to get a new M1 MBP in a few months and can wait until then.

@jackbrannen commented on GitHub (Aug 31, 2021): Hey @waydabber, you are so kind to offer all of this troubleshooting help. I started following your steps above and hit issues installing ddcctl. Truthfully this is more trouble that it's worth to me at this point—I hope to get a new M1 MBP in a few months and can wait until then.

gitea-mirror commented

2026-05-05 05:24:29 -06:00

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@waydabber commented on GitHub (Sep 1, 2021):

All right, no problem. It was beneficial anyway to solve the issue of making a way to start the app if initial DDC read caused an obstacle by introducing safe mode.

I close this issue then now. :)

@waydabber commented on GitHub (Sep 1, 2021): All right, no problem. It was beneficial anyway to solve the issue of making a way to start the app if initial DDC read caused an obstacle by introducing safe mode. I close this issue then now. :)

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[GH-ISSUE #262] Freezes my entire system at every launch—with default preferences #204