If the `invoke` command does not work, it means that the [invoke](https://pypi.org/project/invoke/) python library has not been correctly installed.
Update the installed python packages with PIP:
```
pip3 install -U -r requirements.txt
```
### Invoke Version
If the installed version of invoke is too old, users may see error messages during the installation procedure, such as *"'update' did not receive all required positional arguments!"* (or similar).
As per the [invoke guide](./start/intro.md#invoke), the minimum required version of Invoke is `1.4.0`.
To determine the version of invoke you have installed, run either:
```
invoke --version
```
```
python -m invoke --version
```
If you are running an older version of invoke, ensure it is updated to the latest version.
Most likely you are trying to run the InvenTree server from outside the context of the virtual environment where the required python libraries are installed.
Always activate the virtual environment before running server commands!
If a particular menu / item is not visible after updating InvenTree, or a certain function no longer seems to work, it may be due to your internet browser caching old versions of CSS and JavaScript files.
Before [raising an issue](https://github.com/inventree/inventree/issues), try hard-refreshing the browser cache:
<kbd>Ctrl</kbd> + <kbd>Shift</kbd> + <kbd>R</kbd>
or
<kbd>Ctrl</kbd> + <kbd>F5</kbd>
!!! tip "A Refreshing Solution"
Performing a hard page refresh will remove old javascript files from your browser's cache
A better option is to manage the background worker process using a process manager such as supervisor. Refer to the [production server guide](./start/bare_prod.md).
When installing under [Docker](./start/docker.md), sometimes issues may arise keeping [persistent data](./start/docker.md#persistent-data) in sync. Refer to the [common issues](./start/docker_prod.md#common-issues) section in the docker setup guide for further details.
Permission denied for mkdir: /home/inventree/data/static
```
It means that the user running the InvenTree server does not have permission to create the required directories.
Ensure that the user running the InvenTree server has permission to create the required directories. For example, if running the server as the `inventree` user, ensure that the `inventree` user has permission to create the required directories.
If you are using Docker to run the InvenTree server, ensure that the user that runs the docker daemon has permission to create the required directories in the volume.
