[gbm]

Can confirm happening using Linux Mint 19, I did both a system restore and reverted to calibre 3.28 still same error. This worked on Saturday using 3.31. calibre 3.28 on windows 10 still works.

Now is is good I checked metadata download on widows and it worked one time, then I when back to try it again and now get the same error.

Spoiler:

 $ calibre-debug -g
calibre 3.28  embedded-python: True is64bit: True
Linux-4.15.0-33-generic-x86_64-with-debian-buster-sid Linux ('64bit', 'ELF')
('Linux', '4.15.0-33-generic', '#36-Ubuntu SMP Wed Aug 15 16:00:05 UTC 2018')
Python 2.7.12
Linux: ('debian', 'buster/sid', '')
Interface language: None
Successfully initialized third party plugins: DeDRM (6, 5, 5) && Diaps Editing Toolbag (0, 3, 5) && Quality Check (1, 9, 11) && Hyphenate This! (0, 0, 8) && EpubSplit (2, 4, 0) && Modify ePub (1, 3, 13) && Barnes & Noble (1, 2, 15) && KindleUnpack - The Plugin (0, 81, 5) && Baen (0, 0, 3) && Goodreads (1, 1, 14) && Reading List (1, 6, 6)
Turning off automatic hidpi scaling
QGtkStyle could not resolve GTK. Make sure you have installed the proper libraries.
devicePixelRatio: 1.0
logicalDpi: 96.0 x 96.0
physicalDpi: 85.0837438424 x 85.184279476
Using calibre Qt style: True
QGtkStyle could not resolve GTK. Make sure you have installed the proper libraries.
[0.00] Starting up...
[0.02] Showing splash screen...
[0.28] splash screen shown
[0.28] Initializing db...
[0.39] db initialized
[0.39] Constructing main UI...
libpng warning: iCCP: known incorrect sRGB profile
Looking for desktop notifier support from: org.freedesktop.Notifications
org.freedesktop.Notifications found in 0.0 seconds
[2.78] main UI initialized...
[2.78] Hiding splash screen
DEBUG:    0.0 get_baen_id: match_group= None
[3.22] splash screen hidden
[3.22] Started up in 3.22 seconds with 864 books
DEBUG:    2.1 get_baen_id: match_group= None
Metadata sources cache was recently updated not updating again


calibre, version 3.28.0
ERROR: Download failed: Failed to download metadata. Click Show Details to see details

Traceback (most recent call last):
  File "site-packages/calibre/utils/ipc/simple_worker.py", line 289, in main
  File "site-packages/calibre/ebooks/metadata/sources/worker.py", line 102, in single_identify
  File "site-packages/calibre/ebooks/metadata/sources/update.py", line 79, in patch_plugins
  File "site-packages/calibre/ebooks/metadata/sources/update.py", line 62, in patch_search_engines
  File "<string>", line 11, in <module>
ImportError: No module named polyglot.builtins




$ calibre-debug -g
calibre 3.31  embedded-python: True is64bit: True
Linux-4.15.0-33-generic-x86_64-with-debian-buster-sid Linux ('64bit', 'ELF')
('Linux', '4.15.0-33-generic', '#36-Ubuntu SMP Wed Aug 15 16:00:05 UTC 2018')
Python 2.7.12
Linux: ('debian', 'buster/sid', '')
Interface language: None
Successfully initialized third party plugins: DeDRM (6, 5, 5) && Modify ePub (1, 3, 13) && Barnes & Noble (1, 2, 15) && Baen (0, 0, 3) && Goodreads (1, 1, 14) && Reading List (1, 6, 6) && Quality Check (1, 9, 11) && KindleUnpack - The Plugin (0, 81, 5) && EpubSplit (2, 4, 0) && Hyphenate This! (0, 0, 8) && Diaps Editing Toolbag (0, 3, 5)
Turning off automatic hidpi scaling
QGtkStyle could not resolve GTK. Make sure you have installed the proper libraries.
devicePixelRatio: 1.0
logicalDpi: 96.0 x 96.0
physicalDpi: 85.0837438424 x 85.184279476
Using calibre Qt style: True
QGtkStyle could not resolve GTK. Make sure you have installed the proper libraries.
[0.00] Starting up...
[0.02] Showing splash screen...
[0.29] splash screen shown
[0.29] Initializing db...
[0.39] db initialized
[0.39] Constructing main UI...
libpng warning: iCCP: known incorrect sRGB profile
Looking for desktop notifier support from: org.freedesktop.Notifications
org.freedesktop.Notifications found in 0.0 seconds
[2.75] main UI initialized...
[2.75] Hiding splash screen
DEBUG:    0.0 get_baen_id: match_group= None
[3.18] splash screen hidden
[3.19] Started up in 3.19 seconds with 864 books
DEBUG:    1.5 get_baen_id: match_group= None
Metadata sources cache was recently updated not updating again



calibre, version 3.31.0
ERROR: Download failed: Failed to download metadata. Click Show Details to see details

Traceback (most recent call last):
  File "site-packages/calibre/utils/ipc/simple_worker.py", line 289, in main
  File "site-packages/calibre/ebooks/metadata/sources/worker.py", line 102, in single_identify
  File "site-packages/calibre/ebooks/metadata/sources/update.py", line 79, in patch_plugins
  File "site-packages/calibre/ebooks/metadata/sources/update.py", line 62, in patch_search_engines
  File "<string>", line 11, in <module>
ImportError: No module named polyglot.builtins

calibre-debug -g
calibre 3.28  embedded-python: True is64bit: False
Windows-10-10.0.10240-SP0 Windows ('32bit', 'WindowsPE')
('Windows', '10', '10.0.10240')
Python 2.7.12+
Windows: ('10', '10.0.10240', 'SP0', u'Multiprocessor Free')
Interface language: None
Successfully initialized third party plugins: DeDRM (6, 3, 6) && Quality Check (1, 9, 11) && Generate Cover (1, 5, 21) && Modify ePub (1, 3, 13) && Baen (0, 0, 3) && Barnes & Noble (1, 2, 15) && KindleUnpack - The Plugin (0, 81, 5) && Diaps Editing Toolbag (0, 3, 5) && Hyphenate This! (0, 0, 8) && EpubSplit (2, 4, 0) && Goodreads (1, 1, 14)
Turning on automatic hidpi scaling
devicePixelRatio: 1.0
logicalDpi: 120.0 x 120.0
physicalDpi: 179.624309392 x 172.203389831
Using calibre Qt style: True
[0.00] Starting up...
[0.02] Showing splash screen...
[0.53] splash screen shown
[0.91] Initializing db...
[2.19] db initialized
[2.19] Constructing main UI...
libpng warning: iCCP: known incorrect sRGB profile
[14.09] main UI initialized...
[14.09] Hiding splash screen
DEBUG:    0.0 get_baen_id: match_group= None
[15.95] splash screen hidden
[15.97] Started up in 15.97 seconds with 2958 books
Metadata sources cache was recently updated not updating again



calibre, version 3.28.0
ERROR: Download failed: Failed to download metadata. Click Show Details to see details

Traceback (most recent call last):
  File "site-packages\calibre\utils\ipc\simple_worker.py", line 289, in main
  File "site-packages\calibre\ebooks\metadata\sources\worker.py", line 102, in single_identify
  File "site-packages\calibre\ebooks\metadata\sources\update.py", line 79, in patch_plugins
  File "site-packages\calibre\ebooks\metadata\sources\update.py", line 62, in patch_search_engines
  File "<string>", line 11, in <module>
ImportError: No module named polyglot.builtins

bernie