I'm glad my instructions helped (or maybe ... led you to different problems)
Locales are a foreign topic to me (sorry - bad pun!) as I'm in en-GB and everything just works.
First, remember that locales are not just about 'short date format' - they also control for example the decimal and thousands separators (dot or comma), currency symbol, paper size etc so don't forget that ! Type 'locale' at the Pi prompt to see a list of what gets set.
Second, establish what locale has been used for your historical data in Cumulus 1.9.4. Then will need to try replicate that in CumulusMX.
You have said you are looking for DD/MM/YYYY. But that is strictly incorrect as dd and yyyy should not be capitalised. MM is capitalised to distinguish from minutes (mm). So I think you are looking for dd/MM/yyyy, which means use 2-digit date / 2-digit month / 4-digit year with / as separator. If your old data contains single-digit day and month (1st March comes out as 1/3/2019 rather than 01/03/2019) then you are looking for d/M/yyyy instead of dd/MM/yyyy. The standard US format (which is inherited by many in Canada) uses single-digits with dot-separator ie d.M.yyyy rather than dd.MM.yyyy. For a full list of possible date and time code elements, see
I also saw a note that the en-CA (English Canadian) specification was changed in recent years: "Windows 7 has en-CA short date format configured by default as dd/MM/yyyy, but it changes to yyyy-MM-dd in Windows 8/10. This can cause all kinds of problems in web application pools that handle international languages that are not congruent" though it may be the '.net' version rather than the Windows version. Help! Maybe your data is in the previous en-CA format dd/MM/yyyy, but requesting en-CA on RPi gives & expects yyyy-MM-dd ??? That seems to match with your comment.
If your old data has dd/MM/yyyy and has dot as the decimal separator, can you just leave the RPi in en-GB? Or am I being simplistic?
My today.ini displays date in the format for my locale, followed by the standard ISO format (not based on locale):
and a short extract of May16log.txt shows my date and time formats, use of comma as decimal separator and no thousands separator.
Code: Select all
01/05/16,00:00,5.6,99,5.5,0.0,0.0,0,0.0,0.0,1021.6,1105.8,22.2,36,0.0,5.6,5.6,0.0,0,0.00,0.00,4.6,0,0.0,0,0.0,0.0
01/05/16,00:10,5.6,99,5.5,0.1,0.7,45,0.0,0.3,1021.5,1106.1,22.2,36,0.0,5.6,5.6,0.0,0,0.00,0.00,4.6,0,0.0,0,0.0,0.3
01/05/16,00:20,5.5,99,5.4,0.0,0.0,0,0.0,0.3,1021.7,1106.1,22.2,36,0.0,5.5,5.5,0.0,0,0.00,0.00,4.4,0,0.0,0,0.0,0.3
01/05/16,00:30,5.5,99,5.4,1.0,2.2,310,0.0,0.3,1021.6,1106.1,22.2,36,1.6,5.5,5.5,0.0,0,0.00,0.00,4.1,0,0.0,315,0.0,0.3
01/05/16,00:40,5.5,99,5.4,0.9,2.2,312,3.6,0.6,1021.5,1106.4,22.2,36,0.0,5.5,5.5,0.0,0,0.00,0.00,4.2,0,0.0,0,0.0,0.6
01/05/16,00:50,5.5,99,5.4,0.0,0.7,315,0.0,0.6,1021.5,1106.4,22.2,36,0.0,5.5,5.5,0.0,0,0.00,0.00,4.4,0,0.0,0,0.0,0.6
01/05/16,01:00,5.4,99,5.3,0.0,0.0,0,0.0,0.6,1021.5,1106.4,22.2,36,0.0,5.4,5.4,0.0,0,0.00,0.00,4.3,0,0.0,0,0.0,0.6
01/05/16,01:10,5.3,99,5.2,0.0,0.0,0,3.6,0.9,1021.6,1106.7,22.2,36,0.0,5.3,5.3,0.0,0,0.00,0.00,4.2,0,0.0,0,0.0,0.9
01/05/16,01:20,5.3,99,5.2,0.0,0.0,0,0.0,0.9,1021.6,1106.7,22.2,36,0.0,5.3,5.3,0.0,0,0.00,0.00,4.2,0,0.0,0,0.0,0.9
If your look like this, locale en-GB may be for you.