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: # 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!