Thanks for taking the time to report this! Please always follow https://www.mediawiki.org/wiki/How_to_report_a_bug and include error messages here.

https://bn.wikipedia.org/w/index.php?title=টেমপ্লেট:Arguments&action=edit&uselang=en&debug=true says:

The revision #0 of the page named "টেমপ্লেট:Arguments" does not exist.
This is usually caused by following an outdated history link to a page that has been deleted. Details can be found in the deletion log.

@Aklapper This template was never created on bnwiki. There is no deletion log.

Could you please try to create above template on bnwiki? don't worry about content, write anything and try to save it.

(I don't plan to create templates on bnwiki, as I prefer knowing what I'm doing)

@Aklapper Please clarify because I'm not sure if you think this request is a user problem or a database error that needs to be fixed. It is not possible to create
https://bn.wikipedia.org/wiki/Template:Arguments
On visiting the page, "Error" appears where the title should be. On trying to save an edit, an edit conflict error is shown.

It looks like a database error

It has a page ID (363432) created on 9 June 2014. Between the pages before and after being created there is one missing revision (1637537) so it's probably either that revision or it never had any revision ID

In T281921#7069788, @Peter_James wrote:

It has a page ID (363432) created on 9 June 2014. Between the pages before and after being created there is one missing revision (1637537) so it's probably either that revision or it never had any revision ID

Revision id 1637537 is related to টেমপ্লেট:Resize. See