[Solved] ImportError: No Module Named ‘psycopg2’

Many developers face the issue of the No module named ‘psycopg2’ when they try to take their project to the production level. With the help of this article, we will understand the cause of the error and the possible solutions to avoid them. Let’s dive in.

What is ‘psycopg2’?

‘psycopg2’ is the most popular database adapter dealing in PostgreSQL. Its core is to completely implement the Python DB API 2.0 specification and the thread-safety. That means it can allow several threads to share a standard connection. It can easily handle concurrent insertion and deletion in an application. It can create or destroy lots of connections simultaneously.

Architechture behind ‘psycopg2’

‘psycopg2’ uses a libpq wrapper, which implements the C programming language interface. It consists of a set of library functions that allow client programs to receive the results of the queries passed to the PostgreSQL backend server.

Cause behind the error: No module named ‘psycopg2’

To execute the program smoothly, some pre-requisites should be met. Failing to meet these requirements will trigger import errors during the compilation.

Pre-requisites are :

1. Python Version
   • 3.6 to 3.9
2. PostgreSQL server versions
   • 7.4 to 13
3. PostgreSQL client library version
   • from 9.1
4. C compiler
5. Package such as python-dev or python3-dev to install python header files.
6. libpq-dev package containing libpq header files.
7. pg-config file should be present in the PATH file. It compiles ‘psycopg2‘

If the system does not meet the above requirements, the ‘psycopg2’ module will not be installed, leading to no modules name ‘psycopg2’ error. This error is often viewed by programmers who don’t have a C compiler in their system. As the binaries fail to install, the module will not work.

Resolving the issue: No module named ‘psycopg2’

To resolve the issue, we must satisfy all the pre-requisites laid by the ‘psycopg2’ to meet its build requirements. However, pyscopg2 also provides us with a binary package with its versions of C libraries, libpq, and libssl, which will be used regardless of other libraries available to the client.

Perform these commands to resolve the issue:

pip uninstall psycopg2
pip install psycopg2-binary

Running the above commands will solve the problem, but the installation may fail in a few cases due to a non-supportive environment. Follow these steps to install the precompiled library –

1. Go to the Precompiled Library Packages list.
2. Then download the wheel file (.whl) for the psycopg module.
3. Then use the command pip install <file>.whl to install the library using downloaded wheel file.

Using the above steps will guarantee installing psycopg2 on your computer.

Working On Incorrect Virtual Enviornment?

Many “No module named psycopg2” errors occur due to working on incorrect virtual environments and installing the ‘psycopg2’ on a different environment. Suppose you have two versions of python3 installed, and how will you install ‘psycopg2’ to a specific python?

Use the following command to call your python and install the package in your respective environment –

python3 -m pip install psycopg2

This will ensure that you install the psycopg2 module in the working environment. Hopefully, this resolves the issue. Moreover, if you face the C Compiler issues in this method, use the precompiled method as mentioned last way.

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Resolving No module named ‘psycopg2’ in AWS EC2 lambda/ Linux OS

However, one cannot rely on binary packages if they are using them in production, and we should build the ‘psycopg2’ from the source. Because upgrading the system libraries will not upgrade the libraries used by ‘psycopg2'. Hence, there might be a dependencies error.

One can perform these commands to solve the problem

sudo apt install gcc g++ build-essential
sudo apt install python3-dev
sudo apt install libpq-dev
python -m pip install psycopg2

FAQs on No module named ‘psycopg2’

Conclusion

So, in this way, one can resolve the import error related to the PostgreSQL connection. A quick tip is to keep in mind the requisites we should follow before executing any program. We can permanently activate a python virtual window and maintain that virtual window according to the project’s needs. Now it’s your time to leverage the DB connection and create fantastic projects with ‘psycopg2’ and PostgreSQL.

Bon Codage!