[jackie_w]

Originally Posted by MrSilverstrike

@JSWolf: Here's the full list of each patch that fails to apply if enabled (I've automated the check):

... <snip> ...
- Default ePub sans-serif font (Gill Sans)
- Default ePub serif font (Amasis)

These 2 patches from librmsdk.so.1.0.0.yaml do not work because the list of fonts included in firmware 4.39 onwards changed. You should be able to use the following as replacement patches.

Default ePub sans-serif font (renamed from 'Default ePub sans-serif font (Gill Sans)')

Spoiler:

Default ePub sans-serif font:
  - Enabled: no
  - Description: |
      This patch changes the default ePub sans-serif font from 'Rakuten Sans' to 'Noto Sans'.
      If the book's stylesheet specifies the generic 'font-family:sans-serif;' then
        the ePub reader will try to use the built-in system font 'Rakuten Sans'.
      This patch allows you to change the default to a different sans-serif font
        (built-in or sideloaded).
      N.B. This patch does not affect kepubs.

    # fw 4.32.19501: The font-family name in Replace: must now be the WHOLE name
    #                not just the first few characters of the name.
    # fw 4.34.20097: Kobo removed the 'Gill Sans' font files from the firmware.
    #       You can still use the patch with one of your sideloaded sans-serif fonts.
    #
    # To use a different font, change "Noto%20Sans" in each Replace: string
    #   to another font name (14 characters max).
    # For example, change "Noto%20Sans" to "Trebuchet" to use a sideloaded Trebuchet font.
    # The 3-char string, %20, represents a single space in the font-family name.
    #
    # If your new font name is longer than 14 chars you would also need to:
    #   1. Use a font editor to shorten the internal font-family name to <=14 chars
    #   2. Rename the 4 font filenames to match the new shortened name
    #   3. Copy the 4 renamed font files into the Kobo sideloaded fonts folder
  - FindReplaceString: {Find: "/normal/Rakuten%20Sans", Replace: "/normal/Noto%20Sans"}
  - FindReplaceString: {Find: "/bold/Rakuten%20Sans", Replace: "/bold/Noto%20Sans"}
  - FindReplaceString: {Find: "/italic/Rakuten%20Sans", Replace: "/italic/Noto%20Sans"}
  - FindReplaceString: {Find: "/bolditalic/Rakuten%20Sans", Replace: "/bolditalic/Noto%20Sans"}

Default ePub serif font (renamed from 'Default ePub serif font (Amasis)')

Spoiler:

Default ePub serif font:
  - Enabled: no
  - Description: |
        This patch changes the default ePub serif font from 'Rakuten Serif' to Bitter.
        If the book's stylesheet specifies the generic 'font-family:serif;' then
            the ePub reader will try to use the built-in system font 'Rakuten Serif'.
            'Rakuten Serif' is also the font you see if you select 'Publisher Default' from
            the Kobo [Aa] menu and your epub has not specified any particular font.
        This patch allows you to change the default to a different serif font 
            (built-in or sideloaded).
        N.B. This patch does not affect kepubs.

    # fw 4.32.19501: The font-family name in Replace: must now be the WHOLE name
    #                not just the first few characters of the name.
    # fw 4.34.20097: Kobo removed the 'Amasis' font files from the firmware.
    #       You can still use the patch with one of your sideloaded serif fonts.
    # To use a different font, change "Bitter" in each replacement string
    #   to another font name (15 characters max).
    # For example, change "Bitter" to "Noto%20Serif" to use a sideloaded "Noto Serif" font.
    # The 3-char string, %20, represents a single space in the font-family name.
    #
    # If your new font name is longer than 15 chars you would also need to:
    #   1. Use a font editor to shorten the internal font-family name to <=15 chars
    #   2. Rename the 4 font filenames to match the new shortened name
    #   3. Copy the 4 renamed font files into the Kobo sideloaded fonts folder
  - FindReplaceString: {Find: "/normal/Rakuten%20Serif", Replace: "/normal/Bitter"}
  - FindReplaceString: {Find: "/bold/Rakuten%20Serif", Replace: "/bold/Bitter"}
  - FindReplaceString: {Find: "/italic/Rakuten%20Serif", Replace: "/italic/Bitter"}
  - FindReplaceString: {Find: "/bolditalic/Rakuten%20Serif", Replace: "/bolditalic/Bitter"}

@JSWolf, Please will you update post #1 to include these changes to librmsdk.so.1.0.0.yaml