Why Do I Get a \'Bad Magic Number\' ImportError in Python, and How Can I Fix It?

Understanding the "Bad Magic Number" ImportError

The "Bad magic number" ImportError occurs in Python when an imported pyc file contains an incorrect magic number, which is a marker indicating the file type in UNIX-like systems.

This error can arise due to several reasons:

• Compilation from Incorrect Python Version: Compiling a .py file into a .pyc file using a different Python version than the one used to import it.
• File Manipulation: Editing or corrupting the pyc file.
• Missing or Incompatible Library: Importing a pyc file that is missing a required library or is incompatible with the current Python version.

To resolve this issue, follow these steps:

1. Delete Pyc Files: Delete all .pyc files associated with the imported module. This forces the interpreter to recompile the .py files upon import. You can use the following commands in a UNIX terminal:

   rm *.pyc

   find . -name '*.pyc' -delete

2. Verify Library Dependencies: Ensure that all the required libraries for the module you're importing are installed and compatible with your Python version.
3. Inspect Full Stack Trace: If the issue persists intermittently, carefully examine the full stack trace during the import error. It may reveal insights into the specific cause.

4. Magic Number Values: Refer to the following table for the magic numbers associated with various Python versions:

   Python Version	Magic Number
   1.5, 1.5.1, 1.5.2	20121
   1.6	50428
   2.0, 2.0.1	50823
   2.1, 2.1.1, 2.1.2	60202
   2.2	60717
   2.3a0 (various builds)	62011, 62021, 62041
   2.4a0	62051
   2.4a3	62061
   2.5a0 (various builds)	62071, 62081, 62091, 62092
   2.5b3 (various builds)	62101, 62111
   2.5c1	62121
   2.5c2	62131
   2.6a0	62151
   2.6a1	62161
   2.7a0	62171

Understanding the bad magic number error and its causes will assist you in effectively resolving this issue when encountered.

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