Nodes have difficulty to sync

Created by: M5oul

Nodes have difficulty to sync:

2016-09-11T00:56:49+02:00 - warn: Too old membership
2016-09-11T00:56:49+02:00 - warn: Too old membership
2016-09-11T00:56:49+02:00 - warn: Too old membership
2016-09-11T00:56:49+02:00 - warn: Too old membership
2016-09-11T00:56:49+02:00 - warn:  httpCode=400, ucode=2020, message=Identity has expired and cannot be written in the blockchain anymore.
2016-09-11T00:56:49+02:00 - info: Generating proof-of-work with 4 leading zeros followed by [0-4]... (CPU usage set to 40%)
2016-09-11T00:56:51+02:00 - info: SWITCH: apply side chain #37772-00001219471F51EDCA0CC3A00E375D847C4C566D06EFEEE282AF43D042A8D5B7...
2016-09-11T00:57:00+02:00 - warn: SWITCH: error Error: Membership's number must be greater than last membership of the pubkey
    at Error (native)
    at /opt/duniter/sources/app/lib/rules/global_rules.js:353:15
    at next (native)
    at onFulfilled (/opt/duniter/sources/node_modules/co/index.js:65:19)
    at process._tickCallback (node.js:412:9)
2016-09-11T00:57:03+02:00 - info: External access: 78.227.107.45:8999
2016-09-11T00:57:25+02:00 - info: Next peering signal in 2.5 min
2016-09-11T00:57:28+02:00 - info: SWITCH: get side chain #37772-00001219471F51EDCA0CC3A00E375D847C4C566D06EFEEE282AF43D042A8D5B7...
2016-09-11T00:57:28+02:00 - info: SWITCH: revert main chain to block #37728...
2016-09-11T00:57:31+02:00 - info: SWITCH: apply side chain #37772-00001219471F51EDCA0CC3A00E375D847C4C566D06EFEEE282AF43D042A8D5B7...
2016-09-11T00:57:35+02:00 - info: Mesured max speed is ~24 tests/s. Proof will try with ~10 tests/s.
2016-09-11T00:57:35+02:00 - info: FOUND proof-of-work with 4 leading zeros followed by [0-4]!
2016-09-11T00:57:37+02:00 - warn: Too old membership
2016-09-11T00:57:37+02:00 - warn: Too old membership
2016-09-11T00:57:37+02:00 - warn: Too old membership
2016-09-11T00:57:37+02:00 - warn: Too old membership
2016-09-11T00:57:37+02:00 - warn: Too old membership
2016-09-11T00:57:37+02:00 - warn: Too old membership
2016-09-11T00:57:37+02:00 - warn: Too old membership

There is many fork in the way, that nodes stayed stucked on previous blocks.