Incorrect Base Offset for Dublin Timezone - Discrepancy Between Server and Local Machine

[asad2k]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

There is a discrepancy between the base offset of the Dublin timezone when viewed on the local machine and the server. The local machine is showing the correct base offset of +00:00 for Dublin, while the server is showing a base offset of +01:00.

I see same result on https://dotnetfiddle.net/OpSu7y..

Expected Behavior

Both the local machine and server should show the same time for Dublin with a base offset of 00:00, reflecting the correct time zone.

Steps To Reproduce

Check the current time in the Dublin timezone locally on your machine.
Check the same time in the Dublin timezone on the server.
Notice that the local machine shows the correct time (00:00 offset), but the server shows an incorrect time with a 01:00 offset.

Exceptions (if any)

No response

.NET Version

9

Anything else?

Server: Linux server

Local machine: Windows 10

[martincostello]

My guess would be this is to do with the TZDB data installed on the Linux machine differing compared to what Windows ships with.

[javiercn]

@asad2k thanks for contacting us.

I suspect this has nothing to do with Blazor, but with the time zone database that you are using. If you create a console app, do you get the same results?

[asad2k]

My guess would be this is to do with the TZDB data installed on the Linux machine differing compared to what Windows ships with.

i tried updating tzdata package in the docker image but it says tzdata is already the newest version?

dotnet/aspnetcore#14 1.492 tzdata is already the newest version (2024b-0+deb12u1).

[martincostello]

It could still be intentionally different between Linux and Windows.

[asad2k]

@asad2k thanks for contacting us.

I suspect this has nothing to do with Blazor, but with the time zone database that you are using. If you create a console app, do you get the same results?

yes, console app shows +00:00 for Dublin. I think as @martincostello said this might be intentionally different between linux and windows.

[colejohnson66]

If you have zdump, can you run zdump -v /usr/share/zoneinfo/Europe/Dublin?

[dotnet-policy-service]

Tagging subscribers to this area: @dotnet/area-system-datetime
See info in area-owners.md if you want to be subscribed.

[tarekgh]

@asad2k we need more info to be able to help with this issue. Please send the response of @colejohnson66 comment #112650 (comment) running it on the server. I tried it on Ubuntu v24 and I am seeing base offset is 0. and I am seeing the TZ rules listed as follows. Do you have similar thing

/usr/share/zoneinfo/Europe/Dublin  Sun Mar 30 00:59:59 2025 UT = Sun Mar 30 00:59:59 2025 GMT isdst=0 gmtoff=0
/usr/share/zoneinfo/Europe/Dublin  Sun Mar 30 01:00:00 2025 UT = Sun Mar 30 02:00:00 2025 IST isdst=1 gmtoff=3600
/usr/share/zoneinfo/Europe/Dublin  Sun Oct 26 00:59:59 2025 UT = Sun Oct 26 01:59:59 2025 IST isdst=1 gmtoff=3600
/usr/share/zoneinfo/Europe/Dublin  Sun Oct 26 01:00:00 2025 UT = Sun Oct 26 01:00:00 2025 GMT isdst=0 gmtoff=0

and

apt list -a tzdata
Listing... Done
tzdata/noble-updates,noble-security,now 2024b-0ubuntu0.24.04.1 all [installed,automatic]
tzdata/noble 2024a-2ubuntu1 all