### Steps to reproduce

* Begin of the insertionCreateEnd of the insertion Begin of the deletion Go toEnd of the deletion a meeting series Begin of the insertionusing a user whose time zone is UTCEnd of the insertion Begin of the deletion that was created in Germany (Berlin time, CET)End of the deletion

* Begin of the insertionOpenEnd of the insertion Begin of the deletion EditEnd of the deletion the Begin of the insertionnext two meetingsEnd of the insertion Begin of the deletion template:End of the deletion

* Begin of the insertionAs a different user in a different time zone (eg. CET), editEnd of the insertion Begin of the deletion First, don't changeEnd of the deletion the Begin of the insertionstartEnd of the insertion time Begin of the insertioninEnd of the insertion Begin of the deletion and go back to meeting series index page and observeEnd of the deletion the Begin of the deletion list of planned meetings

* Then, change the time, go back to theEnd of the deletion meeting Begin of the insertiontemplate to an hour earlierEnd of the insertion Begin of the deletion series index page and observe the list of planned meetingsEnd of the deletion


### What is the buggy behavior?

* Begin of the insertionWeird things happen:

End of the insertion Begin of the deletion The meeting series shows the original meeting time in UTC even if it was created and edited in UTC+1 (Europe/Berlin). In the screenast below, it's 10:30 AM.

End of the deletion * Begin of the insertionOne of the existingEnd of the insertion Begin of the deletion Certain plannedEnd of the deletion meetings Begin of the insertionis changed toEnd of the insertion Begin of the deletion inEnd of the deletion the Begin of the insertionnewEnd of the insertion Begin of the deletion series do not show theEnd of the deletion correct time Begin of the deletion

* They show a time that is offset by +1 hour (12:30 PM in the screencast below)

* As a user, I see three different times:

* 10:30 AM UTC (original),End of the deletion

* Begin of the insertionOne ofEnd of the insertion Begin of the deletion 11:30 AM (upcoming andEnd of the deletion the Begin of the insertionpreviously open meeting goes back to the 'Planned sectionEnd of the insertion Begin of the deletion next planned one)End of the deletion

* Begin of the insertionThere are two meetings that are forEnd of the insertion Begin of the deletion 12:30 AM (allEnd of the deletion the Begin of the insertionwrong time (with a -1 hr difference)End of the insertion Begin of the deletion other planned ones)End of the deletion

* The bug might possibly have been introduced by fix #61933.


Begin of the insertion_**Note:** In the attached gif (below) and_ [_video_](https://community.openproject.org/api/v3/attachments/372392/content)_, the time switches to +1 hr for some planned meetings; this is normal since the original meeting was in UTC and therefore the same time in UTC corresponds to two different times (in CET and CEST) after March 20, 2025 due to summer time._

End of the insertion ### What is the expected behavior?

* Begin of the insertionChanging theEnd of the insertion Begin of the deletion TheEnd of the deletion meeting Begin of the insertiontime should should update all open and planned meetings toEnd of the insertion Begin of the deletion series showsEnd of the deletion the Begin of the insertionnewEnd of the insertion Begin of the deletion correctEnd of the deletion time Begin of the insertion

End of the insertion Begin of the deletion zone it was edited/created in

End of the deletion * Begin of the insertionNote:End of the insertion The Begin of the insertionedit screen willEnd of the insertion Begin of the deletion planned future meetings allEnd of the deletion show the Begin of the deletion same, correctEnd of the deletion time Begin of the deletion

* As a user, I should only ever see two different timesEnd of the deletion in the Begin of the insertionuser's _local_End of the insertion Begin of the deletion index page:

* The seriesEnd of the deletion time Begin of the insertion(maybe this is part of the where the error comes from, becuase the template shows the timeEnd of the insertion in the Begin of the insertion_original_ time zone).

End of the insertion Begin of the deletion original timezone (header)

End of the deletion * Begin of the insertionIt should not create duplicateEnd of the insertion Begin of the deletion The local timezone for individualEnd of the deletion meetings Begin of the insertionwith two different times (with -1 hour offset)


End of the insertion Begin of the deletion


End of the deletion ### Screenshots and other files

Begin of the insertion**Note**: There is also a [video version](https://community.openproject.org/api/v3/attachments/372392/content) of this if you want normal speed and play controls.

End of the insertion <img class="op-uc-image op-uc-image_inline" Begin of the insertionsrc="/api/v3/attachments/372377/content">End of the insertion Begin of the deletion src="/api/v3/attachments/371956/content">End of the deletion

### Environment Begin of the insertioninformatioEnd of the insertion Begin of the deletion informationEnd of the deletion

Begin of the insertion**Stage**End of the insertion Begin of the deletion **Community**End of the deletion
**OpenProject Begin of the insertion15.4.1**End of the insertion Begin of the deletion 15.4**End of the deletion

Begin of the insertionCore build: [840508041512de11db03f5c7218bbaafa1ee26b3](https://github.com/opf/openproject/commits/840508041512de11db03f5c7218bbaafa1ee26b3)
Product version: [9bcd01b60849270319af566763391f36b83755e7](https://github.com/opf/saas-openproject/commits/9bcd01b60849270319af566763391f36b83755e7)


End of the insertion **Browser:**
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**Language**
EN