Traceback (most recent call last):
  File "electrum\json_db.py", line 157, in put
  File "json\__init__.py", line 234, in dumps
  File "json\encoder.py", line 202, in encode
MemoryError

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "electrum\gui\qt\main_window.py", line 158, in request_password
  File "electrum\gui\qt\main_window.py", line 2515, in do_import_privkey
  File "electrum\gui\qt\main_window.py", line 2487, in _do_import
  File "electrum\gui\qt\main_window.py", line 2515, in <lambda>
  File "electrum\wallet.py", line 3223, in import_private_keys
  File "electrum\wallet.py", line 3076, in save_keystore
  File "electrum\json_db.py", line 38, in wrapper
  File "electrum\json_db.py", line 159, in put
MemoryError