[d.r.l]

Tried removing all the other format, more particularly epub as their lines were commented out, thinking it could be the source of the error.

Code

import re, zipfile, os
from calibre.ptempfile import PersistentTemporaryDirectory
from calibre.ptempfile import PersistentTemporaryFile
from urllib.parse import urlparse, urlsplit

class TheSkepticalInquirer(BasicNewsRecipe):
    title = u'The Skeptical Inquirer'
    description = 'Investigation of fringe science and paranormal claims.'
    language = 'en' 
    needs_subscription = True 

def build_index(self):
        browser = self.get_browser()

        pdflink = browser.find_link(text_regex=re.compile('https://skepticalinquirer.org/archive/'))

        # Cheat calibre's recipe method, as in post from Starsom17
        self.report_progress(0,_('downloading PDF'))
        response = browser.follow_link(pdflink)
        dir = PersistentTemporaryDirectory()
        pdf_file = PersistentTemporaryFile(suffix='.epub',dir=dir)
        pdf_file.write(response.read())
        pdf_file.close()

        # Get all formats into Calibre's database as one single book entry
        self.report_progress(0.6,_('Adding files to Calibre db'))
        cmd = "calibredb add -1 " + dir
        os.system(cmd)

        return index

Error:

Fetch news from The Skeptical Inquirer
Conversion options changed from defaults:
  verbose: 2
  output_profile: 'tablet'
Resolved conversion options
calibre version: 5.13.0
{'asciiize': False,
 'author_sort': None,
 'authors': None,
 'base_font_size': 0,
 'book_producer': None,
 'change_justification': 'original',
 'chapter': None,
 'chapter_mark': 'pagebreak',
 'comments': None,
 'cover': None,
 'debug_pipeline': None,
 'dehyphenate': True,
 'delete_blank_paragraphs': True,
 'disable_font_rescaling': False,
 'dont_download_recipe': False,
 'dont_split_on_page_breaks': True,
 'duplicate_links_in_toc': False,
 'embed_all_fonts': False,
 'embed_font_family': None,
 'enable_heuristics': False,
 'epub_flatten': False,
 'epub_inline_toc': False,
 'epub_toc_at_end': False,
 'epub_version': '2',
 'expand_css': False,
 'extra_css': None,
 'extract_to': None,
 'filter_css': None,
 'fix_indents': True,
 'flow_size': 260,
 'font_size_mapping': None,
 'format_scene_breaks': True,
 'html_unwrap_factor': 0.4,
 'input_encoding': None,
 'input_profile': <calibre.customize.profiles.InputProfile object at 0x0000023C025F6A30>,
 'insert_blank_line': False,
 'insert_blank_line_size': 0.5,
 'insert_metadata': False,
 'isbn': None,
 'italicize_common_cases': True,
 'keep_ligatures': False,
 'language': None,
 'level1_toc': None,
 'level2_toc': None,
 'level3_toc': None,
 'line_height': 0,
 'linearize_tables': False,
 'lrf': False,
 'margin_bottom': 5.0,
 'margin_left': 5.0,
 'margin_right': 5.0,
 'margin_top': 5.0,
 'markup_chapter_headings': True,
 'max_toc_links': 50,
 'minimum_line_height': 120.0,
 'no_chapters_in_toc': False,
 'no_default_epub_cover': False,
 'no_inline_navbars': False,
 'no_svg_cover': False,
 'output_profile': <calibre.customize.profiles.TabletOutput object at 0x0000023C0261B370>,
 'page_breaks_before': None,
 'prefer_metadata_cover': False,
 'preserve_cover_aspect_ratio': False,
 'pretty_print': True,
 'pubdate': None,
 'publisher': None,
 'rating': None,
 'read_metadata_from_opf': None,
 'remove_fake_margins': True,
 'remove_first_image': False,
 'remove_paragraph_spacing': False,
 'remove_paragraph_spacing_indent_size': 1.5,
 'renumber_headings': True,
 'replace_scene_breaks': '',
 'search_replace': None,
 'series': None,
 'series_index': None,
 'smarten_punctuation': False,
 'sr1_replace': '',
 'sr1_search': '',
 'sr2_replace': '',
 'sr2_search': '',
 'sr3_replace': '',
 'sr3_search': '',
 'start_reading_at': None,
 'subset_embedded_fonts': False,
 'tags': None,
 'test': False,
 'timestamp': None,
 'title': None,
 'title_sort': None,
 'toc_filter': None,
 'toc_threshold': 6,
 'toc_title': None,
 'transform_css_rules': None,
 'unsmarten_punctuation': False,
 'unwrap_lines': True,
 'use_auto_toc': False,
 'verbose': 2}
InputFormatPlugin: Recipe Input running
Downloading recipe urn: custom:1000
Using user agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/87.0.4280.141 Safari/537.36
Traceback (most recent call last):
  File "runpy.py", line 194, in _run_module_as_main
  File "runpy.py", line 87, in _run_code
  File "site.py", line 82, in <module>
  File "site.py", line 77, in main
  File "site.py", line 49, in run_entry_point
  File "calibre\utils\ipc\worker.py", line 216, in main
  File "calibre\gui2\convert\gui_conversion.py", line 34, in gui_convert_recipe
  File "calibre\gui2\convert\gui_conversion.py", line 28, in gui_convert
  File "calibre\ebooks\conversion\plumber.py", line 1105, in run
  File "calibre\customize\conversion.py", line 245, in __call__
  File "calibre\ebooks\conversion\plugins\recipe_input.py", line 139, in convert
  File "calibre\web\feeds\news.py", line 1051, in download
  File "calibre\web\feeds\news.py", line 1228, in build_index
  File "calibre\web\feeds\news.py", line 1659, in parse_feeds
  File "calibre\web\feeds\news.py", line 474, in get_feeds
NotImplementedError