diff --git a/src/sakia/data/processors/blockchain.py b/src/sakia/data/processors/blockchain.py
index 4acd2fead212a85f6be32a44f6250283d47c3ac9..867b07f7cf415fbaf0608e5b33d63567ad66a86f 100644
--- a/src/sakia/data/processors/blockchain.py
+++ b/src/sakia/data/processors/blockchain.py
@@ -155,18 +155,20 @@ class BlockchainProcessor:
         :return: the list of block documents
         :rtype: List[duniterpy.documents.Block]
         """
-        from_block = min(numbers)
-        to_block = max(numbers)
-        count = to_block - from_block
-
-        blocks_data = await self._bma_connector.get(currency, bma.blockchain.blocks, req_args={'count': count,
-                                                                                     'from_': from_block})
-        blocks = []
-        for data in blocks_data:
-            if data['number'] in numbers:
-                blocks.append(Block.from_signed_raw(data["raw"] + data["signature"] + "\n"))
-
-        return blocks
+        if numbers:
+            from_block = min(numbers)
+            to_block = max(numbers)
+            count = to_block - from_block
+
+            blocks_data = await self._bma_connector.get(currency, bma.blockchain.blocks, req_args={'count': count,
+                                                                                         'from_': from_block})
+            blocks = []
+            for data in blocks_data:
+                if data['number'] in numbers:
+                    blocks.append(Block.from_signed_raw(data["raw"] + data["signature"] + "\n"))
+
+            return blocks
+        return []
 
     async def initialize_blockchain(self, currency, log_stream):
         """
diff --git a/src/sakia/data/processors/transactions.py b/src/sakia/data/processors/transactions.py
index b5f9049962c4dbd10818891b87eca03696bf3743..212883409f02dff3e5fe83b702c6c80a88b11ca7 100644
--- a/src/sakia/data/processors/transactions.py
+++ b/src/sakia/data/processors/transactions.py
@@ -1,13 +1,10 @@
 import attr
-import re
 from ..entities import Transaction
 from .nodes import NodesProcessor
 from . import tx_lifecycle
 from ..connectors import BmaConnector
-from duniterpy.api import bma, errors
-from duniterpy.documents import Block, BMAEndpoint
-import asyncio
-import time
+from duniterpy.api import bma
+from duniterpy.documents import Block
 
 
 @attr.s
@@ -122,3 +119,11 @@ class TransactionsProcessor:
         self.run_state_transitions(tx, ([r.status for r in responses], block_doc))
         self.run_state_transitions(tx, ([r.status for r in responses],))
         return result
+
+    def initialize_transactions(self, currency, pubkey):
+        """
+        Request transactions from the network to initialize data for a given pubkey
+        :param str currency:
+        :param str pubkey:
+        """
+        history = await self._bma_connector.get()
\ No newline at end of file
diff --git a/src/sakia/services/identities.py b/src/sakia/services/identities.py
index f9e42f26e91993ff76a09bce54632aacf4a23476..d83926ede9a766b5cbe91f66afe34e81e372e4b6 100644
--- a/src/sakia/services/identities.py
+++ b/src/sakia/services/identities.py
@@ -50,22 +50,6 @@ class IdentitiesService(QObject):
         blockchain_time = self._blockchain_processor.time(self.currency)
         return blockchain_time - cert_time < parameters.sig_window * parameters.avg_gen_time
 
-    async def cert_issuance_delay(self, identity):
-        """
-        Get the remaining time before being able to issue new certification.
-        :param sakia.data.entities.Identity identity: the identity
-        :return: the remaining time
-        """
-        if not identity.written_on:
-            await self.update_certified_by(identity)
-        if len(certified) > 0:
-            latest_time = max([c['cert_time'] for c in certified if c['cert_time']])
-            sig_period = await self._blockchain_processor.parameters(self.currency).sig_period
-            current_time = await self._blockchain_processor.time(self.currency)
-            if current_time - latest_time < sig_period:
-                return sig_period - (current_time - latest_time)
-        return 0
-
     async def load_memberships(self, identity):
         """
         Request the identity data and save it to written identities
@@ -271,7 +255,7 @@ class IdentitiesService(QObject):
         # requirements requests
         for identity in set(need_refresh):
             refresh_futures.append(self.refresh_requirements(identity))
-        await asyncio.gather(refresh_futures)
+        await asyncio.gather(*refresh_futures)
 
     async def requirements(self, currency, pubkey, uid):
         """