With a CD present on CD drive and after pressing "CD Lookup" button on the tool bar an error dialog box with the message:

Error while reading CD:

error while reading CD TOC

appears.

I have tested it with different CDs and Picard versions going from 0.11 to 0.15.1 and the log is mostly the same in all cases:

0.11
D: <sip.voidptr object at 0x011FB660> 20:04:09 Starting Picard 0.11 from 'C:
Program Files
MusicBrainz Picard\\library.zip\\picard
tagger.pyo'
D: <sip.voidptr object at 0x011FB660> 20:04:09 Loading gettext translation, localedir='locale'
D: <sip.voidptr object at 0x011FB660> 20:04:09 Starting the browser integration (port 8000)
E: <sip.voidptr object at 0x011FB660> 20:04:13 Traceback (most recent call last):
File "picard\util\thread.pyo", line 80, in generic_run_item
File "picard\disc.pyo", line 50, in read
DiscError: error while reading the CD TOC

0.12
D: <sip.voidptr object at 0x01F02728> 19:46:36 Starting Picard 0.12 from 'C:
Program Files
MusicBrainz Picard\\library.zip\\picard
tagger.pyo'
D: <sip.voidptr object at 0x01F02728> 19:46:37 Loading gettext translation, localedir='locale'
D: <sip.voidptr object at 0x01F02728> 19:46:37 Plugin directory 'plugins' doesn't exist
D: <sip.voidptr object at 0x01F02728> 19:46:37 Starting the browser integration (port 8000)
E: <sip.voidptr object at 0x01F02728> 19:46:42 Traceback (most recent call last):
File "picard\util\thread.pyo", line 80, in generic_run_item
File "picard\disc.pyo", line 50, in read
DiscError: error while reading the CD TOC

0.14
D: <sip.voidptr object at 0x02036518> 19:52:26 Starting Picard 0.14 from 'C:
Program Files
MusicBrainz Picard\\library.zip\\picard
tagger.pyo'
D: <sip.voidptr object at 0x020365A8> 19:52:26 Loading gettext translation, localedir='locale'
D: <sip.voidptr object at 0x020365A8> 19:52:26 Plugin directory 'plugins' doesn't exist
D: <sip.voidptr object at 0x020365A8> 19:52:26 Starting the browser integration (port 8000)
E: <sip.voidptr object at 0x020365A8> 19:52:26 Traceback (most recent call last):
File "picard\util\thread.pyo", line 80, in generic_run_item
File "picard\disc.pyo", line 50, in read
DiscError: error while reading the CD TOC

0.15
D: <sip.voidptr object at 0x01FDEC98> 19:29:38 Starting Picard 0.15.1 from 'C:
Program Files
MusicBrainz Picard\\library.zip\\picard
tagger.pyo'
D: <sip.voidptr object at 0x01FDED28> 19:29:38 Loading gettext translation, localedir='locale'
D: <sip.voidptr object at 0x01FDED28> 19:29:38 Loading plugin 'classicdiscnumber'
D: <sip.voidptr object at 0x01FDED28> 19:29:38 Loading plugin 'discnumber'
D: <sip.voidptr object at 0x01FDED28> 19:29:38 Loading plugin 'featartist'
D: <sip.voidptr object at 0x01FDED28> 19:29:38 Loading plugin 'titlecase'
D: <sip.voidptr object at 0x01FDED28> 19:29:38 Starting the browser integration (port 8000)
E: <sip.voidptr object at 0x01FDED28> 19:29:47 Traceback (most recent call last):
File "picard\util\thread.pyo", line 59, in run_item
File "picard\disc.pyo", line 51, in read
DiscError: error while reading the CD TOC