[GH-ISSUE #215] Default proxy settings are not updated on system proxy settings change #676

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opened 2026-03-01 17:40:50 +03:00 by kerem · 5 comments

kerem commented

2026-03-01 17:40:50 +03:00

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Originally created by @abukhnin on GitHub (Nov 27, 2017).
Original GitHub issue: https://github.com/aluxnimm/outlookcaldavsynchronizer/issues/215

A synchronization issue occurs when the system proxy settings change.
Reproduced with Outlook CalDav Synchronizer 2.26.0.0, Outlook 2013 on Windows 8.1.

To reporoduce:

Run Outlook with installed Outlook CalDav Synchronizer.
Check "Use system default proxy" in Network settings of a Synchronization profile.
Change system proxy settings. E.g. in my case this happens automatically when I connect to a corporate network.
Initiate synchronization - it will fail. See
log.txt

Restarting Outlook fixes the issue until the next system proxy settings change.

Here is a patch that helps me prevent the issue:
dynamic_proxy_patch.txt

Originally created by @abukhnin on GitHub (Nov 27, 2017). Original GitHub issue: https://github.com/aluxnimm/outlookcaldavsynchronizer/issues/215 A synchronization issue occurs when the system proxy settings change. Reproduced with Outlook CalDav Synchronizer 2.26.0.0, Outlook 2013 on Windows 8.1. To reporoduce: 1. Run Outlook with installed Outlook CalDav Synchronizer. 2. Check "Use system default proxy" in Network settings of a Synchronization profile. 3. Change system proxy settings. E.g. in my case this happens automatically when I connect to a corporate network. 4. Initiate synchronization - it will fail. See [log.txt](https://github.com/aluxnimm/outlookcaldavsynchronizer/files/1507526/log.txt) Restarting Outlook fixes the issue until the next system proxy settings change. Here is a patch that helps me prevent the issue: [dynamic_proxy_patch.txt](https://github.com/aluxnimm/outlookcaldavsynchronizer/files/1507542/dynamic_proxy_patch.txt)

kerem added the

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2026-03-01 17:40:50 +03:00

kerem commented

2026-03-01 17:40:51 +03:00

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@aluxnimm commented on GitHub (Nov 29, 2017):

Thank you, we will look into it.

@aluxnimm commented on GitHub (Nov 29, 2017): Thank you, we will look into it.

kerem commented

2026-03-01 17:40:51 +03:00

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@aluxnimm commented on GitHub (Dec 5, 2018):

Your patch has not the same behaviour. DefaultWebProxy read settings from app.config and as fallback from Windows settings but GetSystemWebProxy() doesn't consider app.config.

@aluxnimm commented on GitHub (Dec 5, 2018): Your patch has not the same behaviour. DefaultWebProxy read settings from app.config and as fallback from Windows settings but GetSystemWebProxy() doesn't consider app.config.

kerem commented

2026-03-01 17:40:51 +03:00

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@abukhnin commented on GitHub (Dec 9, 2018):

I see. I tested my patch with DefaultWebProxy instead of GetSystemWebProxy(), but it didn't work - the proxy wasn't properly set upon connection to a corporate network. I suppose that's because DefaultWebProxy is only set once on application start.
In a comment at https://stackoverflow.com/questions/14887679/whats-the-difference-between-webrequest-defaultwebproxy-and-webrequest-getsyste#comment20889389_14888220 it is suggested to use DefaultWebProxy for "custom proxy configuration" and GetSystemWebProxy() for "use system settings" option.
Maybe indeed these should be separate options along with "use manual proxy configuration"?

@abukhnin commented on GitHub (Dec 9, 2018): I see. I tested my patch with DefaultWebProxy instead of GetSystemWebProxy(), but it didn't work - the proxy wasn't properly set upon connection to a corporate network. I suppose that's because DefaultWebProxy is only set once on application start. In a comment at https://stackoverflow.com/questions/14887679/whats-the-difference-between-webrequest-defaultwebproxy-and-webrequest-getsyste#comment20889389_14888220 it is suggested to use DefaultWebProxy for "custom proxy configuration" and GetSystemWebProxy() for "use system settings" option. Maybe indeed these should be separate options along with "use manual proxy configuration"?

kerem commented

2026-03-01 17:40:51 +03:00

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@aluxnimm commented on GitHub (Dec 9, 2018):

Would be rather confusing to have two different default options, question is if anybody uses app.config settings.

@aluxnimm commented on GitHub (Dec 9, 2018): Would be rather confusing to have two different default options, question is if anybody uses app.config settings.

kerem commented

2026-03-01 17:40:52 +03:00

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@abukhnin commented on GitHub (Dec 9, 2018):

Maybe, name them something like "Static default proxy configuration" and "Dynamic system proxy configuration"?
Besides backward compatibility for those who did use app.config, one more reason to have both these options is to let users prevent delays in particular cases, like this one: https://developercommunity.visualstudio.com/content/problem/108772/webrequestgetsystemwebproxy-occasionally-very-slow.html
I know that extra customization options may indicate unresolved design problems, but here they seem to be justified.

@abukhnin commented on GitHub (Dec 9, 2018): Maybe, name them something like "Static default proxy configuration" and "Dynamic system proxy configuration"? Besides backward compatibility for those who did use app.config, one more reason to have both these options is to let users prevent delays in particular cases, like this one: https://developercommunity.visualstudio.com/content/problem/108772/webrequestgetsystemwebproxy-occasionally-very-slow.html I know that extra customization options may indicate unresolved design problems, but here they seem to be justified.