I haven't been able to utilize the Yasnippet I've been using to override the newer one that Org-Mode created aka '<s' + TAB expansion, which does source blocks in lowercase, which I despise.

I placed my override Yasnippet template in '~/.emacs.d/snippets/org-mode/src'

Mine used to be just fine until I upgraded to Emacs 27.2.
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*Here is the affected Yasnippet that I have placed in '~/.emacs.d/snippets/org-mode/src' whose aim is to just override the default non-Caps version of the same idea:*

# -*- mode: snippet -*- # name: src # key: <s # -- #+BEGIN_SRC $1   $0 #+END_SRC

Here is what I get when I attempt to do "<s TAB" in an Org Mode doc buffer within the modeline:
No such language mode: nil-mode

*What's weird about this is that another similar snippet I did for bash works just fine in comparison, though obviously the user doesn't have to specify the language being used so maybe that's why, this is present in '~/.emacs.d/snippets/org-mode/bashsrc':*

# -*- mode: snippet -*- # name: bashsrc # key: <b # -- #+BEGIN_SRC bash   $0 #+END_SRC

Has anyone else ran into this issue?

I'm guessing its some kind of Org Mode vs Yasnippet issue where Org-mode is expanding it too fast, when it should wait for user input hence the "$1" section.

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*Here's the traceback:*

Debugger entered--Lisp error: (error "No such language mode: nil-mode")

signal(error ("No such language mode: nil-mode"))

error("No such language mode: %s" nil-mode)

org-edit-src-code()

org-babel-do-key-sequence-in-edit-buffer("\11")

org-indent-line()

indent-according-to-mode()

yas--indent-region(115547 115559 #s(yas--snippet :expand-env nil :fields (#s(yas--field :number 1 :start #<marker at 115546 in life.org> :end #<marker at 115546 in life.org> :parent-field nil :mirrors nil :transform nil :modified-p nil :next #s(yas--exit :marker #<marker at 115549 in life.org> :next nil))) :exit #s(yas--exit :marker #<marker at 115549 in life.org> :next nil) :id 3 :control-overlay nil :active-field nil :previous-active-field nil :force-exit nil))

yas--indent(#s(yas--snippet :expand-env nil :fields (#s(yas--field :number 1 :start #<marker at 115546 in life.org> :end #<marker at 115546 in life.org> :parent-field nil :mirrors nil :transform nil :modified-p nil :next #s(yas--exit :marker #<marker at 115549 in life.org> :next nil))) :exit #s(yas--exit :marker #<marker at 115549 in life.org> :next nil) :id 3 :control-overlay nil :active-field nil :previous-active-field nil :force-exit nil))

#f(compiled-function () #<bytecode 0xf63605>)()

funcall(#f(compiled-function () #<bytecode 0xf63605>))

(let nil (funcall '#f(compiled-function () #<bytecode 0xf63605>)))

eval((let nil (funcall '#f(compiled-function () #<bytecode 0xf63605>))))

yas--snippet-create("#+BEGIN_SRC $1\n $0\n#+END_SRC" nil 115534 115534)

yas-expand-snippet(#s(yas--template :key "<s" :content "#+BEGIN_SRC $1\n $0\n#+END_SRC" :name "src" :condition nil :expand-env nil :load-file "/home/sam/.emacs.d/snippets/org-mode/src" :save-file nil :keybinding nil :uuid "src" :menu-binding-pair ((menu-item "src" (lambda nil (interactive) (yas--expand-or-visit-from-menu 'org-mode "src")) :keys "<s =>")) :group nil :perm-group nil :table #s(yas--table :name "org-mode" :hash #<hash-table equal 2/65 0x17ba06d> :uuidhash #<hash-table equal 2/65 0x138c6e1> :parents nil :direct-keymap (keymap))) 115534 115536)

yas--expand-or-prompt-for-template((("src" . #s(yas--template :key "<s" :content "#+BEGIN_SRC $1\n $0\n#+END_SRC" :name "src" :condition nil :expand-env nil :load-file "/home/sam/.emacs.d/snippets/org-mode/src" :save-file nil :keybinding nil :uuid "src" :menu-binding-pair ((menu-item "src" (lambda nil (interactive) (yas--expand-or-visit-from-menu ... "src")) :keys "<s =>")) :group nil :perm-group nil :table #s(yas--table :name "org-mode" :hash #<hash-table equal 2/65 0x17ba06d> :uuidhash #<hash-table equal 2/65 0x138c6e1> :parents nil :direct-keymap (keymap))))) 115534 115536)

yas-expand()

funcall-interactively(yas-expand)

call-interactively(yas-expand nil nil)

command-execute(yas-expand)

Thanks.