Which build are you on? It seems to work for me in build 25609.

Anything strange about the attribute you're using perhaps? What's the one that does get selected?

Hi, 

I use de build 25615.

I also tried it with another attribute and it's the same problem. 

Hi ​@nath ,

I was able to reprocude the problem with FME 2025.1.1 build 25615. It seems to be a bug on Dataset Fanout function in this version of FME.

Very bad...

Okay, that's a shame. I'll have to ask to revert to the previous version because I need it a lot.

Thank you for checking it out.

I created ticket #57772 for this issue. Tagging ​@crystalatsafe.

​@nielsgerrits ,

Thank you for submmiting a support ticket regarding this problem, on behalf of us :-) Hopefully it will be fixed in the next version.

Additional information.

In my observation, the problem occurs on not only Shapefile writer, but also GeoPackage writer. I'm afraid that the problem inpacts on all the writers.

However, the problem didn't occur when running an existing workspace created by FME 2025.0 or eralier, with FME 2025.1.1. It seems that the problem occurs only if you added writer to the workspace and configured dataset fanout onto the writer, with FME 2025.1.1.

Anyway, I would say it's one of the worst bugs we have ever seen. I remember that some critical bugs appeared immediately after major version up in the past too. I strongly hope Safe will enhance their quality control process not to appear critical bugs in future release versions.

Thanks for this update ​@takashi. We would very much like to move to FME 2025.x for server.

But it looks like we need to build all workbenches in 2024.x and then test and publish from 2025.x

2025.1 is not an option because of Python compatibility.

Hi ​@nath, ​@nielsgerrits and ​@takashi This fan-out problem was already fixed for FME 2025.2 but will now also be fixed for FME 2025.1.2, soon to be released.

I very much agree with ​@takashi: “Anyway, I would say it's one of the worst bugs we have ever seen. I remember that some critical bugs appeared immediately after major version up in the past too. I strongly hope Safe will enhance their quality control process not to appear critical bugs in future release versions.”

​@DanAtSafe , FME 2025.1.2 Build 25630 - the latest release version is now available, and I found this description in the Change Log.

I thought that the problem discussed in this thread was fixed in the new release, but in my quick test, it doesn't seem to be fixed yet unfortunately.

See the attachment including a sample dataset and two workspaces created with FME 2025.1.2, which reproduce the problem about dataset fanout configuration on Shapefile writer and GeoPackage writer. I'm afraid that other writers could have the same issue.

Hope the issue will be fixed asap.

It does work for me. But I only use FeatureReaders and FeatureWriters.

​@nielsgerrits , thank you for your feedback.

Have you tested the sample data and the workspace examples I shared in the previous post? It not yet, please try that.

I created and ran the workspace examples with FME 2025.1.2 Build 25630 running on Windows 11.

OK, no problem with FeatureWriter. The problem seems to appear in fanout configuration only on regular writers. 

That might be caused by me. When working with Dan to on this issue, I uploaded a sample workspace demonstrating the error. But I only used FeatureReaders / FeatureWriters as I haven’t used classic Readers / Writers in years...

​@nielsgerrits , it’s not your fault. Safe should check and take final responsibility for a bug fix, even if it was reported from users.