diff --git a/.travis.yml b/.travis.yml
index 646eedd..7234d0c 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -13,7 +13,6 @@ cache:
 - pip
 notifications:
   email: false
-sudo: required
 services:
 - docker
 install:
@@ -37,7 +36,6 @@ branches:
   - /release-v[0-9]+/
 deploy:
   provider: script
-  skip_cleanup: true
   script: python setup.py deploy_docker_bases
   on:
     branch: master
diff --git a/arca/__init__.py b/arca/__init__.py
index c514865..c84afde 100644
--- a/arca/__init__.py
+++ b/arca/__init__.py
@@ -6,4 +6,4 @@
 
 __all__ = ["Arca", "BaseBackend", "VenvBackend", "DockerBackend", "Result", "Task", "CurrentEnvironmentBackend",
            "VagrantBackend"]
-__version__ = "0.3.3"
+__version__ = "0.4.0"
diff --git a/arca/backend/docker.py b/arca/backend/docker.py
index 7b00ee0..1ea1b71 100644
--- a/arca/backend/docker.py
+++ b/arca/backend/docker.py
@@ -305,15 +305,17 @@ def get_or_build_image(self, name: str, tag: str, dockerfile: Union[str, Callabl
 
                 dockerfile_file.unlink()
         except docker.errors.BuildError as e:
+            build_log = []
             for line in e.build_log:
                 if isinstance(line, dict) and line.get("errorDetail") and line["errorDetail"].get("code") in {124, 143}:
                     raise BuildTimeoutError(f"Installing of requirements timeouted after "
                                             f"{self.requirements_timeout} seconds.")
+                build_log.append(line)
 
             logger.exception(e)
 
             raise BuildError("Building docker image failed, see extra info for details.", extra_info={
-                "build_log": e.build_log
+                "build_log": build_log
             })
 
     def get_arca_base(self, pull=True):
@@ -326,11 +328,11 @@ def get_arca_base(self, pull=True):
 
         pyenv_installer = "https://raw.githubusercontent.com/pyenv/pyenv-installer/master/bin/pyenv-installer"
         dockerfile = f"""
-            FROM debian:stretch-slim
+            FROM debian:bullseye-slim
             RUN apt-get update && \
                 apt-get install -y make build-essential libssl-dev zlib1g-dev libbz2-dev \
                                    libreadline-dev libsqlite3-dev wget curl llvm libncurses5-dev libncursesw5-dev \
-                                   xz-utils tk-dev libffi-dev git locales && \
+                                   xz-utils tk-dev libffi-dev git locales libxml2-dev libxmlsec1-dev liblzma-dev && \
                 apt-get clean
 
             RUN sed -i -e 's/# en_US.UTF-8 UTF-8/en_US.UTF-8 UTF-8/' /etc/locale.gen && locale-gen
@@ -349,6 +351,7 @@ def get_arca_base(self, pull=True):
                   rm ~/pyenv-installer && \
                   echo 'export PYENV_ROOT="$HOME/.pyenv"' >> /home/arca/.bash_profile && \
                   echo 'export PATH="$PYENV_ROOT/bin:$PATH"' >> /home/arca/.bash_profile && \
+                  echo 'eval "$(pyenv init --path)"' >> /home/arca/.bash_profile && \
                   echo 'eval "$(pyenv init -)"' >> /home/arca/.bash_profile
 
             USER root
@@ -383,7 +386,6 @@ def get_dockerfile():
                 RUN pyenv update && \
                     pyenv install {python_version}
                 ENV PYENV_VERSION {python_version}
-                ENV PATH "/home/arca/.pyenv/shims:$PATH"
                 RUN pip install --upgrade pip setuptools pipenv
                 CMD bash -i
             """
diff --git a/docs/backends.rst b/docs/backends.rst
index 08e665b..2d6034f 100644
--- a/docs/backends.rst
+++ b/docs/backends.rst
@@ -85,7 +85,7 @@ with ``docker`` (see `documentation <https://docs.docker.com/install/linux/linux
 This backend first creates an image with requirements and dependencies installed so the installation only runs once.
 By default the images are based on `custom images <https://hub.docker.com/r/arcaoss/arca/tags/>`_, which have Python
 and several build tools pre-installed.
-These images are based on ``debian`` (slim ``stretch`` version) and use `pyenv <https://github.com/pyenv/pyenv>`_
+These images are based on ``debian`` (slim ``bullseye`` version) and use `pyenv <https://github.com/pyenv/pyenv>`_
 to install Python.
 You can specify you want to base your images on a different image with the ``inherit_image`` setting.
 
diff --git a/setup.py b/setup.py
index cf910d6..e6cacc7 100644
--- a/setup.py
+++ b/setup.py
@@ -20,7 +20,7 @@ def long_description():
 
 setup(
     name="arca",
-    version="0.3.3",
+    version="0.4.0",
     author="Mikuláš Poul",
     author_email="mikulaspoul@gmail.com",
     description="A library for running Python functions (callables) from git repositories "