iris.load() fails on single time value .grib2 files with KeyError: 'numberOfTimeRange not defined in section 4'

[hydroscopex]

I've stumbled upon an issue when trying to import .grib2 files that only contain a single time value, when trying to re-run a piece of code I had written a while back (probably with iris-grib 0.17.0 or earlier) but which used to run at the time.

I'm currently running:

• iris 3.10.0
• iris-grib 0.20.0
• eccodes 2.38.0
• python 3.12.7

The files i'm trying to load into iris are the output of weather model runs for a single time, such as those that can be found at : https://mf-models-on-aws.org/#arome-france-hd/v1/

See for instance : https://mf-models-on-aws.org/#arome-france-hd/v1/2024-10-12/00/SP1/00H.grib2 (this link will die in a month's time but any similar grib should raise the same error).

When I attempt to load the files in iris with this configuration I get the error :

KeyError: 'numberOfTimeRange not defined in section 4'

with the stack trace included in the attached file stack_trace_KeyError-numberOfTimeRange.txt

I'm not sure where this error might come from, but I'm wondering if it has anything to do with #498 ?

PS : I'm very thankful for this library which simplifys my work a lot !
PS2 : I'm not very well versed in grib files but if anyone can put me on the right path I'd be happy to help solve this issue.

[pp-mo]

Unfortunately I think this is due to a recent breaking change in eccodes, which we are aware of + working on.
See this
I think if you can wind back to eccodes version 2.37 it will fix it. In the meantime, we are working on a fix.

[hydroscopex]

Yes reverting to eccodes 2.37.0 fixes the issue. Thx! Good luck with the fix!