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Q&A Reinstall old Python libraries after update

Every time I run a program I'm used to, I get a bunch of import errors, and have to reinstall the dependencies. As you're presumably aware, the fundamental problem is that each Python installa...

posted 6mo ago by Karl Knechtel‭ · edited 6mo ago by Karl Knechtel‭

Answer

#4: Post edited by

Karl Knechtel‭ · 2024-06-15T10:02:22Z (6 months ago)

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> Every time I run a program I'm used to, I get a bunch of import errors, and have to reinstall the dependencies.
As you're presumably aware, the [fundamental problem](https://software.codidact.com/posts/291675) is that each Python installation is treated as its own separate environment, with its own suite of third-party libraries. Since there still *is* an "old 3.11 site-packages" folder, we can deduce that your "update" to Python installed 3.12, but didn't remove 3.11. This is expected if the 3.11 distribution was included with your Linux distribution - since critical system scripts would have been written and tested for 3.11, and would also need to be updated in order to replace the system Python.
(On the other hand, as Hackysack correctly points out - if these Python installations are coming from your system package manager, you should check what packages they include. Note that these will often be in a separate `dist-packages` folder, rather than `site-packages`.)
As I explained in my answer on the other question, you can *try* hacking `sys.path` to include the old `site-packages` folder, but this is very brittle and likely to produce difficult-to-debug errors.
If you had [set up a virtual environment](https://software.codidact.com/posts/291740), you could [try using the `--upgrade` option](https://docs.python.org/3/library/venv.html#creating-virtual-environments) for `venv`. But to the best of my knowledge, this does not attempt to reinstall third-party libraries; it only reconfigures the venv to use the new Python version.
The most robust option for setting up a new environment - virtual or not - is to freeze the old dependencies, create a new empty environment (if it doesn't already exist), and reinstall the frozen dependencies. **But even this can fail**, if the new Python version isn't supported by specific "pinned" versions of the installed libraries. You may need to edit the `requirements.txt` file to remove or modify version restrictions, which in turn may require doing a bit of research to figure out which versions of a library are acceptable for your use cases.
As for excluding things like `setuptools` and `pip`, this too can be done by editing the `requirements.txt` file from `pip freeze` etc. But there isn't really a good reason to exclude them - they'll be just as useful in the new environment as they were in the old one. You might consider updating both to the latest version, however. In general, the team responsible for these tools does a great job of ensuring that the newest releases of those tools work on the newest versions of Python; on the other hand, eventually they drop support for older Python versions, and older tool versions can't be guaranteed forwards-compatible (since nobody can predict the future).

> Every time I run a program I'm used to, I get a bunch of import errors, and have to reinstall the dependencies.
As you're presumably aware, the [fundamental problem](https://software.codidact.com/posts/291675) is that each Python installation is treated as its own separate environment, with its own suite of third-party libraries. Since there still *is* an "old 3.11 site-packages" folder, we can deduce that your "update" to Python installed 3.12, but didn't remove 3.11. This is expected if the 3.11 distribution was included with your Linux distribution - since critical system scripts would have been written and tested for 3.11, and would also need to be updated in order to replace the system Python.
(On the other hand, as Hackysack correctly points out - if these Python installations are coming from your system package manager, you should check what packages they include - especially check what 3.12 already provides you, before making plans to reinstall everything. Note that distro-provided Python will often put third-party libraries in a separate `dist-packages` folder, rather than `site-packages`.)
As I explained in my answer on the other question, you can *try* hacking `sys.path` to include the old `site-packages` folder, but this is very brittle and likely to produce difficult-to-debug errors.
If you had [set up a virtual environment](https://software.codidact.com/posts/291740), you could [try using the `--upgrade` option](https://docs.python.org/3/library/venv.html#creating-virtual-environments) for `venv`. But to the best of my knowledge, this does not attempt to reinstall third-party libraries; it only reconfigures the venv to use the new Python version.
The most robust option for setting up a new environment - virtual or not - is to freeze the old dependencies, create a new empty environment (if it doesn't already exist), and reinstall the frozen dependencies. **But even this can fail**, if the new Python version isn't supported by specific "pinned" versions of the installed libraries. You may need to edit the `requirements.txt` file to remove or modify version restrictions, which in turn may require doing a bit of research to figure out which versions of a library are acceptable for your use cases.
As for excluding things like `setuptools` and `pip`, this too can be done by editing the `requirements.txt` file from `pip freeze` etc. But there isn't really a good reason to exclude them - they'll be just as useful in the new environment as they were in the old one. You might consider updating both to the latest version, however. In general, the team responsible for these tools does a great job of ensuring that the newest releases of those tools work on the newest versions of Python; on the other hand, eventually they drop support for older Python versions, and older tool versions can't be guaranteed forwards-compatible (since nobody can predict the future).

#3: Post edited by

Karl Knechtel‭ · 2024-06-15T10:01:23Z (6 months ago)

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> Every time I run a program I'm used to, I get a bunch of import errors, and have to reinstall the dependencies.
As you're presumably aware, the [fundamental problem](https://software.codidact.com/posts/291675) is that each Python installation is treated as its own separate environment, with its own suite of third-party libraries. Since there still *is* an "old 3.11 site-packages" folder, we can deduce that your "update" to Python installed 3.12, but didn't remove 3.11. This is expected if the 3.11 distribution was included with your Linux distribution - since critical system scripts would have been written and tested for 3.11, and would also need to be updated in order to replace the system Python.
As I explained in my answer on the other question, you can *try* hacking `sys.path` to include the old `site-packages` folder, but this is very brittle and likely to produce difficult-to-debug errors.
If you had [set up a virtual environment](https://software.codidact.com/posts/291740), you could [try using the `--upgrade` option](https://docs.python.org/3/library/venv.html#creating-virtual-environments) for `venv`. But to the best of my knowledge, this does not attempt to reinstall third-party libraries; it only reconfigures the venv to use the new Python version.
The most robust option for setting up a new environment - virtual or not - is to freeze the old dependencies, create a new empty environment (if it doesn't already exist), and reinstall the frozen dependencies. **But even this can fail**, if the new Python version isn't supported by specific "pinned" versions of the installed libraries. You may need to edit the `requirements.txt` file to remove or modify version restrictions, which in turn may require doing a bit of research to figure out which versions of a library are acceptable for your use cases.
As for excluding things like `setuptools` and `pip`, this too can be done by editing the `requirements.txt` file from `pip freeze` etc. But there isn't really a good reason to exclude them - they'll be just as useful in the new environment as they were in the old one. You might consider updating both to the latest version, however. In general, the team responsible for these tools does a great job of ensuring that the newest releases of those tools work on the newest versions of Python; on the other hand, eventually they drop support for older Python versions, and older tool versions can't be guaranteed forwards-compatible (since nobody can predict the future).

> Every time I run a program I'm used to, I get a bunch of import errors, and have to reinstall the dependencies.
As you're presumably aware, the [fundamental problem](https://software.codidact.com/posts/291675) is that each Python installation is treated as its own separate environment, with its own suite of third-party libraries. Since there still *is* an "old 3.11 site-packages" folder, we can deduce that your "update" to Python installed 3.12, but didn't remove 3.11. This is expected if the 3.11 distribution was included with your Linux distribution - since critical system scripts would have been written and tested for 3.11, and would also need to be updated in order to replace the system Python.
(On the other hand, as Hackysack correctly points out - if these Python installations are coming from your system package manager, you should check what packages they include. Note that these will often be in a separate `dist-packages` folder, rather than `site-packages`.)
As I explained in my answer on the other question, you can *try* hacking `sys.path` to include the old `site-packages` folder, but this is very brittle and likely to produce difficult-to-debug errors.
If you had [set up a virtual environment](https://software.codidact.com/posts/291740), you could [try using the `--upgrade` option](https://docs.python.org/3/library/venv.html#creating-virtual-environments) for `venv`. But to the best of my knowledge, this does not attempt to reinstall third-party libraries; it only reconfigures the venv to use the new Python version.
The most robust option for setting up a new environment - virtual or not - is to freeze the old dependencies, create a new empty environment (if it doesn't already exist), and reinstall the frozen dependencies. **But even this can fail**, if the new Python version isn't supported by specific "pinned" versions of the installed libraries. You may need to edit the `requirements.txt` file to remove or modify version restrictions, which in turn may require doing a bit of research to figure out which versions of a library are acceptable for your use cases.
As for excluding things like `setuptools` and `pip`, this too can be done by editing the `requirements.txt` file from `pip freeze` etc. But there isn't really a good reason to exclude them - they'll be just as useful in the new environment as they were in the old one. You might consider updating both to the latest version, however. In general, the team responsible for these tools does a great job of ensuring that the newest releases of those tools work on the newest versions of Python; on the other hand, eventually they drop support for older Python versions, and older tool versions can't be guaranteed forwards-compatible (since nobody can predict the future).

#2: Post edited by

Karl Knechtel‭ · 2024-06-15T09:59:47Z (6 months ago)

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> Every time I run a program I'm used to, I get a bunch of import errors, and have to reinstall the dependencies.
As you're presumably aware, the [fundamental problem](https://software.codidact.com/posts/291675) is that each Python installation is treated as its own separate environment, with its own suite of third-party libraries. Since there still *is* an "old 3.11 site-packages" folder, we can deduce that your "update" to Python installed 3.12, but didn't remove 3.11. This is expected if the 3.11 distribution was included with your Linux distribution - since critical system scripts would have been written and tested for 3.11, and would also need to be updated in order to replace the system Python.
As I explained in my answer on the other question, you can *try* hacking `sys.path` to include the old `site-packages` folder, but this is very brittle and likely to produce difficult-to-debug errors.
If you had [set up a virtual environment](https://software.codidact.com/posts/291740), you could [try using the `--upgrade` option](https://docs.python.org/3/library/venv.html#creating-virtual-environments) for `venv`. But to the best of my knowledge, this does not attempt to reinstall third-party libraries; it only reconfigures the venv to use the new Python version.
The most robust option for setting up a new environment - virtual or not - is to freeze the old dependencies, create a new empty environment (if it doesn't already exist), and reinstall the frozen dependencies. **But even this can fail**, if the new Python version isn't supported by specific "pinned" versions of the installed libraries. You may need to edit the `requirements.txt` file to remove or modify version restrictions, which in turn may require doing a bit of research to figure out which versions of a library are acceptable for your use cases.

> Every time I run a program I'm used to, I get a bunch of import errors, and have to reinstall the dependencies.
As you're presumably aware, the [fundamental problem](https://software.codidact.com/posts/291675) is that each Python installation is treated as its own separate environment, with its own suite of third-party libraries. Since there still *is* an "old 3.11 site-packages" folder, we can deduce that your "update" to Python installed 3.12, but didn't remove 3.11. This is expected if the 3.11 distribution was included with your Linux distribution - since critical system scripts would have been written and tested for 3.11, and would also need to be updated in order to replace the system Python.
As I explained in my answer on the other question, you can *try* hacking `sys.path` to include the old `site-packages` folder, but this is very brittle and likely to produce difficult-to-debug errors.
If you had [set up a virtual environment](https://software.codidact.com/posts/291740), you could [try using the `--upgrade` option](https://docs.python.org/3/library/venv.html#creating-virtual-environments) for `venv`. But to the best of my knowledge, this does not attempt to reinstall third-party libraries; it only reconfigures the venv to use the new Python version.
The most robust option for setting up a new environment - virtual or not - is to freeze the old dependencies, create a new empty environment (if it doesn't already exist), and reinstall the frozen dependencies. **But even this can fail**, if the new Python version isn't supported by specific "pinned" versions of the installed libraries. You may need to edit the `requirements.txt` file to remove or modify version restrictions, which in turn may require doing a bit of research to figure out which versions of a library are acceptable for your use cases.
As for excluding things like `setuptools` and `pip`, this too can be done by editing the `requirements.txt` file from `pip freeze` etc. But there isn't really a good reason to exclude them - they'll be just as useful in the new environment as they were in the old one. You might consider updating both to the latest version, however. In general, the team responsible for these tools does a great job of ensuring that the newest releases of those tools work on the newest versions of Python; on the other hand, eventually they drop support for older Python versions, and older tool versions can't be guaranteed forwards-compatible (since nobody can predict the future).

#1: Initial revision by

Karl Knechtel‭ · 2024-06-15T09:55:32Z (6 months ago)

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> Every time I run a program I'm used to, I get a bunch of import errors, and have to reinstall the dependencies.

As you're presumably aware, the [fundamental problem](https://software.codidact.com/posts/291675) is that each Python installation is treated as its own separate environment, with its own suite of third-party libraries. Since there still *is* an "old 3.11 site-packages" folder, we can deduce that your "update" to Python installed 3.12, but didn't remove 3.11. This is expected if the 3.11 distribution was included with your Linux distribution - since critical system scripts would have been written and tested for 3.11, and would also need to be updated in order to replace the system Python.

As I explained in my answer on the other question, you can *try* hacking `sys.path` to include the old `site-packages` folder, but this is very brittle and likely to produce difficult-to-debug errors.

If you had [set up a virtual environment](https://software.codidact.com/posts/291740), you could [try using the `--upgrade` option](https://docs.python.org/3/library/venv.html#creating-virtual-environments) for `venv`. But to the best of my knowledge, this does not attempt to reinstall third-party libraries; it only reconfigures the venv to use the new Python version.

The most robust option for setting up a new environment - virtual or not - is to freeze the old dependencies, create a new empty environment (if it doesn't already exist), and reinstall the frozen dependencies. **But even this can fail**, if the new Python version isn't supported by specific "pinned" versions of the installed libraries. You may need to edit the `requirements.txt` file to remove or modify version restrictions, which in turn may require doing a bit of research to figure out which versions of a library are acceptable for your use cases.

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