Armory 0.95.1 BUILD DATABASE forever

[kamamuri]

armorylog repeats continually:

2017-02-18 15:10 (ERROR) -- SDM.pyc:791 - ValueError in bkgd req top blk
Traceback (most recent call last):
  File "SDM.pyc", line 765, in __backgroundRequestTopBlock
  File "bitcoinrpc_jsonrpc\authproxy.pyc", line 105, in __call__
  File "json\__init__.pyc", line 351, in loads
  File "json\decoder.pyc", line 366, in decode
  File "json\decoder.pyc", line 384, in raw_decode
ValueError: No JSON object could be decoded

Any idea what to do?