[Mobile] DateTime.Now returns incorrect local time for one hour after entering DST in 39 locales. #16395

jgold6 · 2019-08-21T21:57:10Z

Steps to Reproduce

Open the attached test project
Set the device time on your target device to 3/8/2020 2:00 AM Central Standard Time. Note that it jumps to 3:00 AM as there is no 2:00 AM on 3/8/2020.
If deploying to a simulator, you will have to set the time on the host workstation to set the system time for an emulator or simulator, whether iOS or Android. depending on the device/workstation, you may not be able to directly select Central Standard Time for the time zone, but may have to select, e.g. Kansas City, MO. Worth noting is that CST in Canada works correctly, and it is only CST in the US where this issue occurs, along with 38 other locales noted below.
Deploy the test app to your target device.
Observe the time in the app UI compared to the system time in the device status bar.

DateTimeNowDSTTest.zip

Current Behavior

Time shown is one hour earlier than is shown by the system time.

Expected Behavior

Time shown in the app matches the system time in the system status bar.

Notes

Although this issue only occurs on Xamarin.iOS and Xamarin.Android, it is a mono issue.
I reported this issue against Xam.iOS and Xam.Android in two DevDiv reports (958935 and 958936), and an iOS engineer (@mandel-macaque ) confirmed this is a mono issue and believes he identified the problem area. Thus I am opening this new issue against Mono and will be closing the DevDiv issues against XI and XA.
This issue has been reported for other locales and DST change times/dates in this closed mono issue:
#9664
Initially the above issue was about 2019 Spring and Fall changeovers. The Fall 2019 DST changeover seems to be correct, but I still notice issues for Spring 2020 as noted below.

Affected locales and details of when changeover is supposed to occur for each locale:

Cuba, Havana (Cuba Standard Time):    Jumps ahead at 12:00 AM on 3/8/2020 to 1:00 AM
US, Kansas City, MO (US Central Time):    Jumps ahead at 2:00 AM on 3/8/2020 to 3:00 AM
Anchorage, AK (Alaska Time):    Jumps ahead at 2:00 AM on 3/8/2020 to 3:00 AM
Azores ST (Ponta Delgada, Portugal):    Jumps ahead at 12:00 AM on 3/29/2020 to 1:00 AM
Iran, Tehran (Iran ST):    Jumps ahead at 12:00 AM on 3/21/2020 to 1:00 AM
Israel, Jerusalem (Israel ST):    Jumps ahead at 2:00 AM on 3/27/2020 to 3:00 AM
Jordan, Amman (Eastern European ST):    Jumps ahead at 12:00 AM on 3/27/2020 to 1:00 AM
Albania, Tirana (Central European ST):    Jumps ahead at 2:00 AM on 3/29/2020 to 3:00 AM
Austria, Vienna (Central European ST):    Jumps ahead at 2:00 AM on 3/29/2020 to 3:00 AM
Belgium, Brussels (Central European ST):    Jumps ahead at 2:00 AM on 3/29/2020 to 3:00 AM
Bulgaria, Sofia (Eastern European ST):    Jumps ahead at 3:00 AM on 3/29/2020 to 4:00 AM
Czechia, Prague (Central European ST):    Jumps ahead at 2:00 AM on 3/29/2020 to 3:00 AM
Denmark, Copenhagen (Central European ST):    Jumps ahead at 2:00 AM on 3/29/2020 to 3:00 AM
Estonia, Tallinn (Eastern European ST):    Jumps ahead at 3:00 AM on 3/29/2020 to 4:00 AM
France, Paris (Central European ST):    Jumps ahead at 2:00 AM on 3/29/2020 to 3:00 AM
Germany, Berlin (Central European ST):    Jumps ahead at 2:00 AM on 3/29/2020 to 3:00 AM
Greece, Athens (Eastern European ST):    Jumps ahead at 3:00 AM on 3/29/2020 to 4:00 AM
Guernsey (UK) - cannot find in macOS time zone settings - tested only in Android:    Jumps ahead at 1:00 AM on 3/29/2020 to 2:00 AM
Holy See, Vatican City (Central European ST):    Jumps ahead at 2:00 AM on 3/29/2020 to 3:00 AM
Hungary, Budapest (Central European ST):    Jumps ahead at 2:00 AM on 3/29/2020 to 3:00 AM
Ireland, Dublin (Greenwich Mean Time -> Irish Standard Time):    Jumps ahead at 1:00 AM on 3/29/2020 to 2:00 AM
UK, Douglas, Isle of Man (GMT+1:00):    Jumps ahead at 1:00 AM on 3/29/2020 to 2:00 AM
Italy, Rome (Central European ST):    Jumps ahead at 2:00 AM on 3/29/2020 to 3:00 AM
Jersey (UK) - cannot find in macOS time zone settings - tested only in Android:    Jumps ahead at 2:00 AM on 3/29/2020 to 3:00 AM
Latvia, Riga (Eastern European ST):    Jumps ahead at 3:00 AM on 3/29/2020 to 4:00 AM
Lithuania, Vilnius (Eastern European ST):    Jumps ahead at 3:00 AM on 3/29/2020 to 4:00 AM
Luxembourg, Luxembourg (Central European ST):    Jumps ahead at 2:00 AM on 3/29/2020 to 3:00 AM
Malta, Valletta (Central European ST):    Jumps ahead at 2:00 AM on 3/29/2020 to 3:00 AM
Moldova, Chişinău (Eastern European ST):    Jumps ahead at 2:00 AM on 3/29/2020 to 3:00 AM
Monaco, Monaco (Central European ST):    Jumps ahead at 2:00 AM on 3/29/2020 to 3:00 AM
Netherlands, Amsterdam (Central European ST):    Jumps ahead at 2:00 AM on 3/29/2020 to 3:00 AM
Norway, Oslo (Central European ST):    Jumps ahead at 2:00 AM on 3/29/2020 to 3:00 AM
Poland, Warsaw (Central European ST):    Jumps ahead at 2:00 AM on 3/29/2020 to 3:00 AM
Portugal, Lisbon (Western European ST):    Jumps ahead at 2:00 AM on 3/29/2020 to 3:00 AM
San Marino, San Marino (Central European ST):    Jumps ahead at 2:00 AM on 3/29/2020 to 3:00 AM
Slovakia, Bratislava (Central European ST):    Jumps ahead at 2:00 AM on 3/29/2020 to 3:00 AM
Spain, Madrid (Central European ST):    Jumps ahead at 2:00 AM on 3/29/2020 to 3:00 AM
Ukraine, Kiev (Eastern European ST):    Jumps ahead at 3:00 AM on 3/29/2020 to 4:00 AM
United Kingdom, London (British ST):    Jumps ahead at 1:00 AM on 3/29/2020 to 2:00 AM

On which platforms did you notice this

Issue does not occur when using Desktop Mono. See notes above.

[ ] macOS
[ ] Linux
[ ] Windows
[x] iOS
[x] Android

Version Used:

Mono 6.0.0.319
Also tested Mono 6.4.0.81

Xam.Android: Version: 9.4.1.0
Also tested: 9.5.0.27

Xamarin.iOS: Version: 12.14.0.114
Also tested: 12.16.0.5

The text was updated successfully, but these errors were encountered:

jgold6 · 2019-08-21T22:00:31Z

There is also this old, related issue that is still open: #10014

steveisok · 2019-08-21T23:02:22Z

@mandel-macaque When you get a chance, please share w/ @MaximLipnin what you did.

Addresses an issue with jumping into DST for some time zones when the incorrect date-time offset is returned for date-time in UTC (which comes from DateTime.Now). The fix is to just check if the incoming date-time is in UTC. Also added a set of tests for some time zones to verify jumping into DST in general. Fixes #16395

…incorrect date-time offset is returned for date-time in UTC (which comes from DateTime.Now). The fix is to just check if the incoming date-time is in UTC Also I added set of tests for some time zones but they verify jumping into DST in general. Fixes mono#16395 Backport of mono#16430

There is an issue with jumping into DST for some time zones when the incorrect date-time offset is returned for date-time in UTC (which comes from DateTime.Now). The fix is to just check if the incoming date-time is in UTC Also I added set of tests for some time zones but they verify jumping into DST in general. Fixes #16395 Backport of #16430

…incorrect date-time offset is returned for date-time in UTC (which comes from DateTime.Now). The fix is to just check if the incoming date-time is in UTC Also I added set of tests for some time zones but they verify jumping into DST in general. Fixes mono#16395 Backport of mono#16430

Changes: mono/mono@6d40f13...c99adb9 Context: mono/mono#16395 Fix time zone issue when jumping into DST [threads] clear small_id_key TLS when unregistering a thread

There is an issue with jumping into DST for some time zones when the incorrect date-time offset is returned for date-time in UTC (which comes from DateTime.Now). The fix is to just check if the incoming date-time is in UTC Also I added set of tests for some time zones but they verify jumping into DST in general. Fixes #16395 Backport of #16430

Changes: mono/mono@6d40f13...c99adb9 Context: mono/mono#16395 Fix time zone issue when jumping into DST [threads] clear small_id_key TLS when unregistering a thread

Changes: mono/mono@7af64d1...5608fe0 Context: mono/mono#16395 Context: mono/mono#16486 Context: mono/mono#16712 Context: mono/mono#17064 Context: xamarin/xamarin-macios#7005

tetri · 2019-11-11T14:02:28Z

America/Sao_Paulo still wrong with an aborted DST change in 2019 October and November

steveisok · 2019-11-13T13:54:07Z

@MaximLipnin Can you test this out? If confirmed, open a new issue and link to this one.

MaximLipnin · 2019-11-13T14:21:10Z

@tetri Could you share the details?

Changes: mono/api-snapshot@fc50bc4...45a61d9 $ git diff --shortstat fc50bc4f...45a61d93 22 files changed, 775 insertions(+), 474 deletions(-) Changes: dotnet/cecil@a6c8f5e...a6a7f5c $ git diff --shortstat a6c8f5e1...a6a7f5c0 55 files changed, 818 insertions(+), 530 deletions(-) Changes: mono/corefx@1f87de3...49f1c45 $ git diff --shortstat e4f7102b...49f1c453 38 files changed, 1171 insertions(+), 419 deletions(-) Changes: dotnet/linker@ebe2a1f...e8d054b $ git diff --shortstat ebe2a1f4...e8d054bf 137 files changed, 5360 insertions(+), 1781 deletions(-) Changes: mono/mono@8946e49...18920a8 $ git diff --shortstat 8946e49a...18920a83 1811 files changed, 47240 insertions(+), 48331 deletions(-) Changes: xamarin/xamarin-android-api-compatibility@a61271e...50a3c52 $ git diff --shortstat a61271e0...50a3c52d 1 file changed, 2 insertions(+), 791 deletions(-) Fixes: #3619 Context: https://dev.azure.com/devdiv/DevDiv/_workitems/edit/1005448 Context: https://devdiv.visualstudio.com/DefaultCollection/DevDiv/_workitems/edit/967582 Context: https://github.com/dotnet/coreclr/issues/26370 Context: https://github.com/dotnet/coreclr/issues/26479 Context: https://github.com/dotnet/corefx/issues/40455 Context: https://github.com/dotnet/corefx/issues/40578 Context: mono/mono#7377 Context: mono/mono#12421 Context: mono/mono#12586 Context: mono/mono#14080 Context: mono/mono#14725 Context: mono/mono#14772 Context: mono/mono#15261 Context: mono/mono#15262 Context: mono/mono#15263 Context: mono/mono#15307 Context: mono/mono#15308 Context: mono/mono#15310 Context: mono/mono#15646 Context: mono/mono#15687 Context: mono/mono#15805 Context: mono/mono#15992 Context: mono/mono#15994 Context: mono/mono#15999 Context: mono/mono#16032 Context: mono/mono#16034 Context: mono/mono#16046 Context: mono/mono#16192 Context: mono/mono#16308 Context: mono/mono#16310 Context: mono/mono#16369 Context: mono/mono#16380 Context: mono/mono#16381 Context: mono/mono#16395 Context: mono/mono#16411 Context: mono/mono#16415 Context: mono/mono#16486 Context: mono/mono#16570 Context: mono/mono#16605 Context: mono/mono#16616 Context: mono/mono#16689 Context: mono/mono#16701 Context: mono/mono#16712 Context: mono/mono#16742 Context: mono/mono#16759 Context: mono/mono#16803 Context: mono/mono#16808 Context: mono/mono#16824 Context: mono/mono#16876 Context: mono/mono#16879 Context: mono/mono#16918 Context: mono/mono#16943 Context: mono/mono#16950 Context: mono/mono#16974 Context: mono/mono#17004 Context: mono/mono#17017 Context: mono/mono#17038 Context: mono/mono#17040 Context: mono/mono#17083 Context: mono/mono#17084 Context: mono/mono#17133 Context: mono/mono#17139 Context: mono/mono#17151 Context: mono/mono#17180 Context: mono/mono#17278 Context: mono/mono#17549 Context: mono/mono#17569 Context: mono/mono#17665 Context: mono/mono#17687 Context: mono/mono#17737 Context: mono/mono#17790 Context: mono/mono#17924 Context: mono/mono#17931 Context: https://github.com/mono/mono/issues/26758 Context: https://github.com/mono/mono/issues/37913 Context: xamarin/xamarin-macios#7005

Addresses an issue with jumping into DST for some time zones when the incorrect date-time offset is returned for date-time in UTC (which comes from DateTime.Now). The fix is to just check if the incoming date-time is in UTC. Also added a set of tests for some time zones to verify jumping into DST in general. Fixes mono#16395

steveisok added the area-BCL: mscorlib label Aug 21, 2019

steveisok assigned MaximLipnin Aug 21, 2019

steveisok added this to the 2019-08 (6.6.xx) milestone Aug 21, 2019

rootwyrm mentioned this issue Aug 26, 2019

Remove/Update deprecated TZs for #16415 #16450

Merged

marek-safar added the needs more info label Sep 12, 2019

MaximLipnin mentioned this issue Sep 23, 2019

Fix time zone issue when jumping into DST #16430

Merged

steveisok closed this as completed in #16430 Sep 24, 2019

steveisok mentioned this issue Sep 24, 2019

[2019-08] Fix time zone issue when jumping into DST #17027

Merged

steveisok mentioned this issue Sep 25, 2019

[2019-06] Fix time zone issue when jumping into DST #17062

Merged

jonpryor added a commit to jonpryor/xamarin-android that referenced this issue Sep 25, 2019

Bump to mono/mono@c99adb97

657d1a5

Changes: mono/mono@6d40f13...c99adb9 Context: mono/mono#16395 Fix time zone issue when jumping into DST [threads] clear small_id_key TLS when unregistering a thread

jonpryor mentioned this issue Sep 25, 2019

Bump to mono/mono/2019-08@c99adb97 dotnet/android#3691

Merged

jonpryor added a commit to dotnet/android that referenced this issue Sep 26, 2019

Bump to mono/mono@c99adb97 (#3691)

080c7c0

Changes: mono/mono@6d40f13...c99adb9 Context: mono/mono#16395 Fix time zone issue when jumping into DST [threads] clear small_id_key TLS when unregistering a thread

marek-safar removed the needs more info label Sep 26, 2019

jonpryor added a commit to dotnet/android that referenced this issue Sep 27, 2019

Bump to mono/mono@c99adb97 (#3691)

8abdcf1

Changes: mono/mono@6d40f13...c99adb9 Context: mono/mono#16395 Fix time zone issue when jumping into DST [threads] clear small_id_key TLS when unregistering a thread

jonpryor added a commit to dotnet/android that referenced this issue Sep 27, 2019

Bump to mono/mono@5608fe0a

0618c96

Changes: mono/mono@7af64d1...5608fe0 Context: mono/mono#16395 Context: mono/mono#16486 Context: mono/mono#16712 Context: mono/mono#17064 Context: xamarin/xamarin-macios#7005

jonpryor mentioned this issue Sep 27, 2019

Bump to mono/mono/2019-06@5608fe0a dotnet/android#3701

Merged

jonpryor added a commit to dotnet/android that referenced this issue Oct 1, 2019

Bump to mono/mono@5608fe0a

5e714bf

Changes: mono/mono@7af64d1...5608fe0 Context: mono/mono#16395 Context: mono/mono#16486 Context: mono/mono#16712 Context: mono/mono#17064 Context: xamarin/xamarin-macios#7005

MaximLipnin mentioned this issue Oct 10, 2019

ConvertTimeFromUtc returns an invalid time in the hour after a DST change #17218

Closed

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

[Mobile] DateTime.Now returns incorrect local time for one hour after entering DST in 39 locales. #16395

[Mobile] DateTime.Now returns incorrect local time for one hour after entering DST in 39 locales. #16395

jgold6 commented Aug 21, 2019

jgold6 commented Aug 21, 2019 •

edited

Loading

steveisok commented Aug 21, 2019

tetri commented Nov 11, 2019

steveisok commented Nov 13, 2019

MaximLipnin commented Nov 13, 2019

[Mobile] DateTime.Now returns incorrect local time for one hour after entering DST in 39 locales. #16395

[Mobile] DateTime.Now returns incorrect local time for one hour after entering DST in 39 locales. #16395

Comments

jgold6 commented Aug 21, 2019

Steps to Reproduce

Current Behavior

Expected Behavior

Notes

Affected locales and details of when changeover is supposed to occur for each locale:

On which platforms did you notice this

jgold6 commented Aug 21, 2019 • edited Loading

steveisok commented Aug 21, 2019

tetri commented Nov 11, 2019

steveisok commented Nov 13, 2019

MaximLipnin commented Nov 13, 2019

jgold6 commented Aug 21, 2019 •

edited

Loading