I get the same error. Here's the output I get when I click "Next" on step 2 of 5:

hp-wificonfig[3828]: debug: hp:/usb/Deskjet_F4500_series?serial=CN08BC211X05H5: back_end:hp is_hp:True bus:usb model:Deskjet_F4500_series serial:CN08BC211X05H5 dev_file: host: zc: port:1
hp-wificonfig[3828]: debug: hp:/usb/Deskjet_F4500_series?serial=CN08BC211X05H5: back_end:hp is_hp:True bus:usb model:Deskjet_F4500_series serial:CN08BC211X05H5 dev_file: host: zc: port:1
hp-wificonfig[3828]: debug: Device URI: hp:/usb/Deskjet_F4500_series?serial=CN08BC211X05H5
hp-wificonfig[3828]: debug: Printer: None
hp-wificonfig[3828]: debug: Connecting to com.hplip.StatusService (try #1)...
hp-wificonfig[3828]: debug: hp:/usb/Deskjet_F4500_series?serial=CN08BC211X05H5: back_end:hp is_hp:True bus:usb model:Deskjet_F4500_series serial:CN08BC211X05H5 dev_file: host: zc: port:1
hp-wificonfig[3828]: debug: URI: backend=hp, is_hp=True, bus=usb, model=Deskjet_F4500_series, serial=CN08BC211X05H5, dev=, host=, port=1
hp-wificonfig[3828]: debug: Model/UI model: Deskjet_F4500_series/HP Deskjet f4500 Series
hp-wificonfig[3828]: debug: hp:/usb/Deskjet_F4500_series?serial=CN08BC211X05H5: back_end:hp is_hp:True bus:usb model:Deskjet_F4500_series serial:CN08BC211X05H5 dev_file: host: zc: port:1
hp-wificonfig[3828]: debug: Re-reading CUPS printer queue information.
hp-wificonfig[3828]: debug: Sending request on wifi config channel...
hp-wificonfig[3828]: debug: 0000:  3c 3f 78 6d 6c 20 76 65 72 73 69 6f 6e 3d 22 31  <?xml version="1
hp-wificonfig[3828]: debug: 0010:  2e 30 22 20 65 6e 63 6f 64 69 6e 67 3d 22 75 74  .0" encoding="ut
hp-wificonfig[3828]: debug: 0020:  66 2d 38 22 3f 3e 0a 3c 57 69 46 69 43 6f 6e 66  f-8"?>.<WiFiConf
hp-wificonfig[3828]: debug: 0030:  69 67 20 78 6d 6c 6e 73 3d 22 68 74 74 70 3a 2f  ig xmlns="http:/
hp-wificonfig[3828]: debug: 0040:  2f 77 77 77 2e 68 70 2e 63 6f 6d 2f 73 63 68 65  /www.hp.com/sche
hp-wificonfig[3828]: debug: 0050:  6d 61 73 2f 69 6d 61 67 69 6e 67 2f 63 6e 63 2f  mas/imaging/cnc/
hp-wificonfig[3828]: debug: 0060:  64 63 73 6c 2f 32 30 30 36 2f 30 35 2f 57 69 66  dcsl/2006/05/Wif
hp-wificonfig[3828]: debug: 0070:  69 43 6f 6e 66 69 67 22 3e 0a 3c 47 65 74 41 64  iConfig">.<GetAd
hp-wificonfig[3828]: debug: 0080:  61 70 74 6f 72 4c 69 73 74 52 65 71 75 65 73 74  aptorListRequest
hp-wificonfig[3828]: debug: 0090:  3e 0a 3c 2f 47 65 74 41 64 61 70 74 6f 72 4c 69  >.</GetAdaptorLi
hp-wificonfig[3828]: debug: 00a0:  73 74 52 65 71 75 65 73 74 3e 0a 3c 2f 57 69 46  stRequest>.</WiF
hp-wificonfig[3828]: debug: 00b0:  69 43 6f 6e 66 69 67 3e                          iConfig>
hp-wificonfig[3828]: debug: Opening device: hp:/usb/Deskjet_F4500_series?serial=CN08BC211X05H5 (not for printing)
hp-wificonfig[3828]: debug: I/O mode=3
hp-wificonfig[3828]: debug: device-id=1
hp-wificonfig[3828]: debug: Opened device: hp (backend=hp:/usb/Deskjet_F4500_series?serial=CN08BC211X05H5, is_hp=True, bus=usb, model=Deskjet_F4500_series, dev=, serial=CN08BC211X05H5, host=, port=1)
hp-wificonfig[3828]: debug: Opening HP-WIFICONFIG channel...
hp-wificonfig[3828]: debug: channel-id=43
hp-wificonfig[3828]: debug: Writing 184 bytes to channel 43 (device-id=1)...
hp-wificonfig[3828]: debug: Result code=0
hp-wificonfig[3828]: debug: Wrote 184 bytes.
hp-wificonfig[3828]: debug: Reading response on wifi config channel...
hp-wificonfig[3828]: debug: Reading channel 43 (device-id=1, bytes_to_read=16384, allow_short=True, timeout=30)...
hp-wificonfig[3828]: debug: Result code=0
hp-wificonfig[3828]: debug: Allowed short read of 520 of 16384 bytes complete.
hp-wificonfig[3828]: debug: Saved 520 total bytes to stream.
hp-wificonfig[3828]: debug: Reading channel 43 (device-id=1, bytes_to_read=16384, allow_short=True, timeout=1)...
hp-wificonfig[3828]: debug: Result code=0
hp-wificonfig[3828]: debug: End of data
hp-wificonfig[3828]: debug: Saved 0 total bytes to stream.
hp-wificonfig[3828]: debug: 0000:  3c 3f 78 6d 6c 20 76 65 72 73 69 6f 6e 3d 22 31  <?xml version="1
hp-wificonfig[3828]: debug: 0010:  2e 30 22 20 65 6e 63 6f 64 69 6e 67 3d 22 75 74  .0" encoding="ut
hp-wificonfig[3828]: debug: 0020:  66 2d 38 22 3f 3e 3c 57 69 46 69 43 6f 6e 66 69  f-8"?><WiFiConfi
hp-wificonfig[3828]: debug: 0030:  67 20 78 6d 6c 6e 73 3d 22 68 74 74 70 3a 2f 2f  g xmlns="http://
hp-wificonfig[3828]: debug: 0040:  77 77 77 2e 68 70 2e 63 6f 6d 2f 73 63 68 65 6d  www.hp.com/schem
hp-wificonfig[3828]: debug: 0050:  61 73 2f 69 6d 61 67 69 6e 67 2f 63 6e 63 2f 64  as/imaging/cnc/d
hp-wificonfig[3828]: debug: 0060:  63 73 6c 2f 32 30 30 36 2f 30 35 2f 57 69 66 69  csl/2006/05/Wifi
hp-wificonfig[3828]: debug: 0070:  43 6f 6e 66 69 67 22 3e 3c 47 65 74 41 64 61 70  Config"><GetAdap
hp-wificonfig[3828]: debug: 0080:  74 6f 72 4c 69 73 74 52 65 73 70 6f 6e 73 65 3e  torListResponse>
hp-wificonfig[3828]: debug: 0090:  3c 41 64 61 70 74 6f 72 4c 69 73 74 4c 65 6e 67  <AdaptorListLeng
hp-wificonfig[3828]: debug: 00a0:  74 68 3e 31 3c 2f 41 64 61 70 74 6f 72 4c 69 73  th>1</AdaptorLis
hp-wificonfig[3828]: debug: 00b0:  74 4c 65 6e 67 74 68 3e 3c 41 64 61 70 74 6f 72  tLength><Adaptor
hp-wificonfig[3828]: debug: 00c0:  4c 69 73 74 3e 3c 41 64 61 70 74 6f 72 49 6e 66  List><AdaptorInf
hp-wificonfig[3828]: debug: 00d0:  6f 3e 3c 41 64 61 70 74 6f 72 49 44 3e 30 3c 2f  o><AdaptorID>0</
hp-wificonfig[3828]: debug: 00e0:  41 64 61 70 74 6f 72 49 44 3e 3c 41 64 61 70 74  AdaptorID><Adapt
hp-wificonfig[3828]: debug: 00f0:  6f 72 54 79 70 65 3e 57 69 66 69 45 6d 62 65 64  orType>WifiEmbed
hp-wificonfig[3828]: debug: 0100:  64 65 64 3c 2f 41 64 61 70 74 6f 72 54 79 70 65  ded</AdaptorType
hp-wificonfig[3828]: debug: 0110:  3e 3c 41 64 61 70 74 6f 72 53 74 61 74 65 3e 41  ><AdaptorState>A
hp-wificonfig[3828]: debug: 0120:  63 74 69 76 65 4c 69 6e 6b 3c 2f 41 64 61 70 74  ctiveLink</Adapt
hp-wificonfig[3828]: debug: 0130:  6f 72 53 74 61 74 65 3e 3c 41 64 61 70 74 6f 72  orState><Adaptor
hp-wificonfig[3828]: debug: 0140:  50 72 65 73 65 6e 63 65 3e 50 6c 75 67 67 65 64  Presence>Plugged
hp-wificonfig[3828]: debug: 0150:  49 6e 3c 2f 41 64 61 70 74 6f 72 50 72 65 73 65  In</AdaptorPrese
hp-wificonfig[3828]: debug: 0160:  6e 63 65 3e 3c 41 64 61 70 74 6f 72 4e 61 6d 65  nce><AdaptorName
hp-wificonfig[3828]: debug: 0170:  3e 57 69 66 69 30 3c 2f 41 64 61 70 74 6f 72 4e  >Wifi0</AdaptorN
hp-wificonfig[3828]: debug: 0180:  61 6d 65 3e 3c 4d 41 43 41 64 64 72 65 73 73 3e  ame><MACAddress>
hp-wificonfig[3828]: debug: 0190:  64 34 38 35 36 34 39 32 64 32 32 32 3c 2f 4d 41  d4856492d222</MA
hp-wificonfig[3828]: debug: 01a0:  43 41 64 64 72 65 73 73 3e 3c 2f 41 64 61 70 74  CAddress></Adapt
hp-wificonfig[3828]: debug: 01b0:  6f 72 49 6e 66 6f 3e 3c 2f 41 64 61 70 74 6f 72  orInfo></Adaptor
hp-wificonfig[3828]: debug: 01c0:  4c 69 73 74 3e 3c 45 72 72 6f 72 52 65 74 75 72  List><ErrorRetur
hp-wificonfig[3828]: debug: 01d0:  6e 3e 4f 4b 3c 2f 45 72 72 6f 72 52 65 74 75 72  n>OK</ErrorRetur
hp-wificonfig[3828]: debug: 01e0:  6e 3e 3c 2f 47 65 74 41 64 61 70 74 6f 72 4c 69  n></GetAdaptorLi
hp-wificonfig[3828]: debug: 01f0:  73 74 52 65 73 70 6f 6e 73 65 3e 3c 2f 57 69 46  stResponse></WiF
hp-wificonfig[3828]: debug: 0200:  69 43 6f 6e 66 69 67 3e                          iConfig>
hp-wificonfig[3828]: debug: Read 520 bytes.
hp-wificonfig[3828]: debug: Turning on wireless radio...
[0, u'Wifi0', u'ActiveLink', u'PluggedIn']
hp-wificonfig[3828]: debug: Sending request on wifi config channel...
hp-wificonfig[3828]: debug: 0000:  3c 3f 78 6d 6c 20 76 65 72 73 69 6f 6e 3d 22 31  <?xml version="1
hp-wificonfig[3828]: debug: 0010:  2e 30 22 20 65 6e 63 6f 64 69 6e 67 3d 22 75 74  .0" encoding="ut
hp-wificonfig[3828]: debug: 0020:  66 2d 38 22 3f 3e 0a 3c 57 69 46 69 43 6f 6e 66  f-8"?>.<WiFiConf
hp-wificonfig[3828]: debug: 0030:  69 67 20 78 6d 6c 6e 73 3d 22 68 74 74 70 3a 2f  ig xmlns="http:/
hp-wificonfig[3828]: debug: 0040:  2f 77 77 77 2e 68 70 2e 63 6f 6d 2f 73 63 68 65  /www.hp.com/sche
hp-wificonfig[3828]: debug: 0050:  6d 61 73 2f 69 6d 61 67 69 6e 67 2f 63 6e 63 2f  mas/imaging/cnc/
hp-wificonfig[3828]: debug: 0060:  64 63 73 6c 2f 32 30 30 36 2f 30 35 2f 57 69 66  dcsl/2006/05/Wif
hp-wificonfig[3828]: debug: 0070:  69 43 6f 6e 66 69 67 22 3e 0a 3c 53 65 74 41 64  iConfig">.<SetAd
hp-wificonfig[3828]: debug: 0080:  61 70 74 6f 72 50 6f 77 65 72 52 65 71 75 65 73  aptorPowerReques
hp-wificonfig[3828]: debug: 0090:  74 3e 0a 3c 41 64 61 70 74 6f 72 49 44 3e 30 3c  t>.<AdaptorID>0<
hp-wificonfig[3828]: debug: 00a0:  2f 41 64 61 70 74 6f 72 49 44 3e 0a 3c 50 6f 77  /AdaptorID>.<Pow
hp-wificonfig[3828]: debug: 00b0:  65 72 53 74 61 74 65 3e 50 6f 77 65 72 4f 6e 3c  erState>PowerOn<
hp-wificonfig[3828]: debug: 00c0:  2f 50 6f 77 65 72 53 74 61 74 65 3e 0a 3c 2f 53  /PowerState>.</S
hp-wificonfig[3828]: debug: 00d0:  65 74 41 64 61 70 74 6f 72 50 6f 77 65 72 52 65  etAdaptorPowerRe
hp-wificonfig[3828]: debug: 00e0:  71 75 65 73 74 3e 0a 3c 2f 57 69 46 69 43 6f 6e  quest>.</WiFiCon
hp-wificonfig[3828]: debug: 00f0:  66 69 67 3e                                      fig>
hp-wificonfig[3828]: debug: Writing 244 bytes to channel 43 (device-id=1)...
hp-wificonfig[3828]: debug: Result code=0
hp-wificonfig[3828]: debug: Wrote 244 bytes.
hp-wificonfig[3828]: debug: Reading response on wifi config channel...
hp-wificonfig[3828]: debug: Reading channel 43 (device-id=1, bytes_to_read=16384, allow_short=True, timeout=30)...
hp-wificonfig[3828]: debug: Result code=0
hp-wificonfig[3828]: debug: Allowed short read of 213 of 16384 bytes complete.
hp-wificonfig[3828]: debug: Saved 213 total bytes to stream.
hp-wificonfig[3828]: debug: Reading channel 43 (device-id=1, bytes_to_read=16384, allow_short=True, timeout=1)...
hp-wificonfig[3828]: debug: Result code=0
hp-wificonfig[3828]: debug: End of data
hp-wificonfig[3828]: debug: Saved 0 total bytes to stream.
hp-wificonfig[3828]: debug: 0000:  3c 3f 78 6d 6c 20 76 65 72 73 69 6f 6e 3d 22 31  <?xml version="1
hp-wificonfig[3828]: debug: 0010:  2e 30 22 20 65 6e 63 6f 64 69 6e 67 3d 22 75 74  .0" encoding="ut
hp-wificonfig[3828]: debug: 0020:  66 2d 38 22 3f 3e 3c 57 69 46 69 43 6f 6e 66 69  f-8"?><WiFiConfi
hp-wificonfig[3828]: debug: 0030:  67 20 78 6d 6c 6e 73 3d 22 68 74 74 70 3a 2f 2f  g xmlns="http://
hp-wificonfig[3828]: debug: 0040:  77 77 77 2e 68 70 2e 63 6f 6d 2f 73 63 68 65 6d  www.hp.com/schem
hp-wificonfig[3828]: debug: 0050:  61 73 2f 69 6d 61 67 69 6e 67 2f 63 6e 63 2f 64  as/imaging/cnc/d
hp-wificonfig[3828]: debug: 0060:  63 73 6c 2f 32 30 30 36 2f 30 35 2f 57 69 66 69  csl/2006/05/Wifi
hp-wificonfig[3828]: debug: 0070:  43 6f 6e 66 69 67 22 3e 3c 53 65 74 41 64 61 70  Config"><SetAdap
hp-wificonfig[3828]: debug: 0080:  74 6f 72 50 6f 77 65 72 52 65 73 70 6f 6e 73 65  torPowerResponse
hp-wificonfig[3828]: debug: 0090:  3e 3c 45 72 72 6f 72 52 65 74 75 72 6e 3e 4f 4b  ><ErrorReturn>OK
hp-wificonfig[3828]: debug: 00a0:  3c 2f 45 72 72 6f 72 52 65 74 75 72 6e 3e 3c 2f  </ErrorReturn></
hp-wificonfig[3828]: debug: 00b0:  53 65 74 41 64 61 70 74 6f 72 50 6f 77 65 72 52  SetAdaptorPowerR
hp-wificonfig[3828]: debug: 00c0:  65 73 70 6f 6e 73 65 3e 3c 2f 57 69 46 69 43 6f  esponse></WiFiCo
hp-wificonfig[3828]: debug: 00d0:  6e 66 69 67 3e                                   nfig>
hp-wificonfig[3828]: debug: Read 213 bytes.
Traceback (most recent call last):
  File "/usr/share/hplip/ui4/wifisetupdialog.py", line 704, in NextButton_clicked
    self.showNetworkPage()
  File "/usr/share/hplip/ui4/wifisetupdialog.py", line 273, in showNetworkPage
    self.adaptor_id, self.adapterName, state, presence =  self.wifiObj.setAdaptorPower(self.dev, adaptor_list )
ValueError: need more than 1 value to unpack