date_display_format will lead to exception for some format characters

[domsson]

The config option date_display_format is handed over to the PHP date() function, which accepts a certain list of format characters. However, when I tried to change this option to 'Y m', the page will throw an exception:

An exception has been thrown during the rendering of a template ("DateTime::__construct(): Failed to parse time string (2016 06) at position 5 (0): Unexpected character"). 

Which points to plugins/archives/templates/partials/archives.html.twig, line 5.

Also:

• When using a slightly different string, 'Y-m' (dash between), it works as expected
• When using Kanji, it will throw an exception again: '年Y月m'

The expected behavior is that any format character/ string, as outlined in the PHP documentation (see above) can be used for this option and no exception is thrown. At the very least, better documentation is needed to understand what format characters can be used or can't be used (and why).

[mahagr]

DateTime only supports few predefined formats, so no, you cannot use arbitrary date strings.