Dear Stardiviner,

I used the "scimax" configuration. Scimax's maintainer, John Kitchin, helped me out to find the root cause of the problem, i.e. the following addition to " python-font-lock-keywords":

(setq python-font-lock-keywords
(append python-font-lock-keywords
'(;; this is the full string.
;; group 1 is the quote type and a closing quote is matched
;; group 2 is the string part
(
;; "f\\(['\"]\\{1,3\\}\\)\\([^\\1]+?\\)\\1"
"f\\(['\"]\\{1,3\\}\\)\\(.+?\\)\\1"
;; these are the {keywords}
("{[^}]*?}"
;; Pre-match form
(progn (goto-char (match-beginning 0)) (match-end 0))
;; Post-match form
(goto-char (match-end 0))
;; face for this match
(0 font-lock-variable-name-face t))))))

Commenting out this code snippet, the fontfying / HTML-export problem goes away.

Cheers,

sebastian

On Tue, Nov 3, 2020 at 6:50 AM stardiviner <numbchild@gmail.com> wrote:

I have same problem sometimes in different babel languages.
I would like to know what caused this problem too.
Can you send me a message after you solved problem? Thanks in advance. :) smile

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On Mon, Nov 2, 2020 at 2:26 AM Sebastian Gimeno <changimeno@gmail.com> wrote:
Hi,

I am using emacs 27.1 and org-plus-contrib 20201026.
I am having problems with the fontification of python and ipython source blocks when the code contains curly brackets "{}" (other course blocks are ok). For instance, the following snippet
#+BEGIN_SRC python :results drawer
import matplotlib.pyplot as plt
plt.plot([1,2,3])
plt.show()
a=1
print("a={}".format{a})
#+END_SRC
does not fontify correctly in either python or ipython source blocks.

As a consequence, when exporting the org file to HTML (C-c C-e h h), it fails with the following message:
font-lock-fontify-keywords-region: Invalid function: #<subr progn>
If changing the code snippet to:
#+BEGIN_SRC python :results drawer
import matplotlib.pyplot as plt
plt.plot([1,2,3])
plt.show()
a=1
print("a=%s" % a)
#+END_SRC
the block fontifies and the file is exported to HTML correctly.

Can you reproduce this behaviour?

Many thanks in advance!