It seems you're using the struts2-bootstrap-plugin, with the bootstrap theme;
it also seems that the bootstrap theme is unprovided of the freemarker template for the <s:datetextfield />
tag.
Following the logic, the solution is to use a theme (for that tag only) that is provided of the appropriate .ftl
, in the following way:
<s:datetextfield format="dd-MM-yyyy" theme="simple" />
This however is a non-standard situation... it's the first time I see it happens. There is also a JIRA report about this, WW-4434.
I'm not sure what that tag does since I've neved used it and the documentation is broken, but if it's just about textfields, dates and datepickers, consider using native HTML5 datepickers (<s:textfield type="date"/>
) with appropriate fallbacks.