1. I used monero-wallet-gui to import a paper wallet. Synchronization started from the beginning.

 2. Synchronization ran very fast and perfectly well until the moment when my funds appeared, more or less (between "Blocks remaining: 5500" and "Blocks remaining: 4000).

 3. However, from that moment on, synchronization slowed down very much and, worse, the number of blocks remaining started slowly increasing, not decreasing.

 4. Being a Mac user (OS X Yosemite, 10.10.5), I followed the instructions that I've found here: https://monero.stackexchange.com/questions/4462/my-blockchain-is-stuck-how-do-i-unstuck-it

 5. More specifically, 

a) After rebooting my Mac and before starting the GUI, I deleted the p2pstate.bin file. This did not help: the number of blocks remaining was still increasing.

b) So I stopped the daemon and I added "--block-sync-size 20" as daemon startup flag. I then restarted the daemon. This also did not help: the number of blocks remaining was still increasing.

c) So I checked bitmonerolog and I noticed this message: "cryptonote_core/cryptonote_core.cpp:1123	Last scheduled hard fork time shows a daemon update is needed now"

Question: any ideas on how to solve the problem? Does 5.c above is the problem? In case, how can I solve it? How can I update daemon?