diff --git a/app/config.ini b/app/config.ini
index fe952f8..5a97d75 100644
--- a/app/config.ini
+++ b/app/config.ini
@@ -3,7 +3,7 @@
 debug = true
 
 # This is a unique ID that distinguish the Credential Issuer instance
-uid = Credential Issuer 01
+uid = issuer_identifier
 
 # The abs path of the file where the keypair of the CI is stored
 # WARNING: if it does not exists will be created the first time
@@ -22,4 +22,4 @@ AUTH_USERNAME = demo
 AUTH_PASSWORD = demo
 
 # Database
-SQLALCHEMY_DATABASE_URI = sqlite:////app/app/test.db
\ No newline at end of file
+SQLALCHEMY_DATABASE_URI = sqlite:////app/app/test.db
diff --git a/app/contracts b/app/contracts
index ee33864..a62ecba 160000
--- a/app/contracts
+++ b/app/contracts
@@ -1 +1 @@
-Subproject commit ee33864ed36d30e52b326f2f622c813a3f0b446e
+Subproject commit a62ecba9231438d821b788fcabdf26575b665286
diff --git a/app/zencontract.py b/app/zencontract.py
index 306c276..594aa69 100644
--- a/app/zencontract.py
+++ b/app/zencontract.py
@@ -1,7 +1,6 @@
 from pathlib import Path
 
 from zenroom import zenroom
-from zenroom.zenroom import Error
 
 from app.config.config import BaseConfig
 
@@ -41,34 +40,32 @@ def get_contract(self):
         contract = contracts_dir.joinpath(self.name).read_text()
         for k, v in self.placeholder.items():
             contract = contract.replace(f"'{k}'", f"'{v}'")
-        return contract.encode()
+        return contract
 
     def execute(self):
         if config.getboolean("debug"):  # pragma: no cover
             log.debug("+" * 50)
             log.debug("EXECUTING %s" % self.name)
             log.debug("+" * 50)
-            log.debug("DATA: %s" % self.data())
-            log.debug("KEYS: %s" % self.keys())
-            log.debug("CODE: \n%s" % self.zencode.decode())
-        try:
-            result, errors = zenroom.execute(
-                self.zencode, keys=self._keys, data=self._data
-            )
-            self._error = errors
-            return result.decode()
-        except Error:
-            return None
+            log.debug("DATA: %s" % self._data)
+            log.debug("KEYS: %s" % self._keys)
+            log.debug("CODE: \n%s" % self.zencode)
+
+        result, errors = zenroom.zencode_exec(
+            script=self.zencode, keys=self._keys, data=self._data
+        )
+        self._error = errors
+        return result
 
     def keys(self, keys=None):
         if keys:
-            self._keys = keys.encode()
-        return self._keys.decode() if self._keys else None
+            self._keys = keys
+        return self._keys
 
     def data(self, data=None):
         if data:
-            self._data = data.encode()
-        return self._data.decode() if self._data else None
+            self._data = data
+        return self._data
 
     def errors(self):
         return self._error
diff --git a/setup.cfg b/setup.cfg
index 2a08712..9dc95b4 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -2,7 +2,7 @@
 test=pytest
 
 [tool:pytest]
-addopts = --cov=app --cov-report term-missing
+addopts = --maxfail=1 --cov=app --cov-report term-missing
 env =
     DDDC_CREDENTIAL_ISSUER_CONFIGFILE=/home/puria/src/dddc-credential-issuer/app/test.ini
 
diff --git a/setup.py b/setup.py
index 6e5f80a..53b98d0 100644
--- a/setup.py
+++ b/setup.py
@@ -8,9 +8,9 @@
     packages=find_packages(),
     install_requires=[
         "bunch==1.0.1",
-        "fastapi==0.7.1",
+        "fastapi==0.33.0",
         "pytest_runner==4.4",
-        "zenroom==0.2.5",
+        "zenroom==1.0.5",
         "pre-commit==1.14.4",
         "python-multipart==0.0.5",
         "pyjwt==1.7.1",
diff --git a/start.sh b/start.sh
index 61cc504..d8f1269 100755
--- a/start.sh
+++ b/start.sh
@@ -1,4 +1,4 @@
 #!/bin/sh
 
 docker build -t dddc-credential-issuer .
-docker run --rm -p 80:80 -e APP_MODULE="app.main:api" -e LOG_LEVEL="debug" -it dddc-credential-issuer
+docker run --rm -p 5000:80 -e APP_MODULE="app.main:api" -e LOG_LEVEL="debug" -it dddc-credential-issuer