ERROR MESSAGE WHILE SAVING (making it impossible to save)

[alexislitvine]

An error message appears while saving a tile, making it impossible to save.

We tried on Safari, Firefox, and Edge - all with the same error message. Can you help @danrademacher @jeffreyameyer ?

Repro Steps

1. Go to Project#28, e.g. tile#136
2. Add a start date to the existing N7 road
3. Try to save
4. See error

**Screenshots **

![image_2023_10_24T09_23_27_900Z](

https://github.com/OpenHistoricalMap/issues/assets/94073388/e71104c1-f99b-4571-b516-eb33fd1435d9)

[Rub21]

hey @alexislitvine , thanks for reporting the issue!

I have been trying to recreate the issues, but it did not happen in my end, for my test I used Firefox and Safari!

My editions were in: Project #28, Task #136

I was able to save my changes!!

• I have added the following dates in a way : start_date=01/01/1800 and end_date=31/12/1900 https://www.openhistoricalmap.org/way/198665032

• I have added only the start date in a way : start_date=01/01/1800
  https://www.openhistoricalmap.org/way/198665034

• I have added a new N 7 road : start_date=01/01/1800
  https://www.openhistoricalmap.org/way/199786227

Note: Maybe the dates are not accurate, but I can update those according to the dates that you want to add. Also could you guide us through the process of recreating the issue maybe the dates that you are including, step by step?

cc. @batpad

[alexislitvine]

Hi @Rub21 -- I have just found the culprit!! The issue was caused by someone editing the date of a very long segment that crossed multiple tiles at the same time. My edits could not be saved as the date for the segment in question had already been changed by another user and therefore should not be displayed any longer. Hence the 404-type error. Does that make sense?
Although this makes sense, it can be very annoying during a large mapping event when lots of users are editing at the same time. Could we by default cut all segments on tile boundaries to avoid this problem?

[Rub21]

My edits could not be saved as the date for the segment in question had already been changed by another user and therefore should not be displayed any longer. Hence the 404-type error. Does that make sense?

Yes, your explanation makes sense. In openHistoricalMap's system, when you attempt to save edits, conflicts can arise if the data you're working with in memory is outdated due to recent modifications by another user. This version mismatch for specific objects is likely what triggers the 404-type error.

Could we by default cut all segments on tile boundaries to avoid this problem?

Automatically cutting road segments at tile boundaries isn't be posible for the current software, Only the mappers can decide if they want to break roads into smaller chunks.