Why do I get "Pickle - EOFError: Ran out of input" reading an empty file?

Question

Most of the answers here have dealt with how to mange EOFError exceptions, which is really handy if you're unsure about whether the pickled object is empty or not.

However, if you're surprised that the pickle file is empty, it could be because you opened the filename through 'wb' or some other mode that could have over-written the file.

for example:

filename = 'cd.pkl'
with open(filename, 'wb') as f:
    classification_dict = pickle.load(f)

This will over-write the pickled file. You might have done this by mistake before using:

...
open(filename, 'rb') as f:

And then got the EOFError because the previous block of code over-wrote the cd.pkl file.

When working in Jupyter, or in the console (Spyder) I usually write a wrapper over the reading/writing code, and call the wrapper subsequently. This avoids common read-write mistakes, and saves a bit of time if you're going to be reading the same file multiple times through your travails

I would check that the file is not empty first:

import os

scores = {} # scores is an empty dict already

if os.path.getsize(target) > 0:      
    with open(target, "rb") as f:
        unpickler = pickle.Unpickler(f)
        # if file is not empty scores will be equal
        # to the value unpickled
        scores = unpickler.load()

Also open(target, 'a').close() is doing nothing in your code and you don't need to use ;.

It is very likely that the pickled file is empty.

It is surprisingly easy to overwrite a pickle file if you're copying and pasting code.

For example the following writes a pickle file:

pickle.dump(df,open('df.p','wb'))

And if you copied this code to reopen it, but forgot to change 'wb' to 'rb' then you would overwrite the file:

df=pickle.load(open('df.p','wb'))

The correct syntax is

df=pickle.load(open('df.p','rb'))

As you see, that's actually a natural error ..

A typical construct for reading from an Unpickler object would be like this ..

try:
    data = unpickler.load()
except EOFError:
    data = list()  # or whatever you want

EOFError is simply raised, because it was reading an empty file, it just meant End of File ..

You can catch that exception and return whatever you want from there.

open(target, 'a').close()
scores = {};
try:
    with open(target, "rb") as file:
        unpickler = pickle.Unpickler(file);
        scores = unpickler.load();
        if not isinstance(scores, dict):
            scores = {};
except EOFError:
    return {}

if path.exists(Score_file):
      try : 
         with open(Score_file , "rb") as prev_Scr:

            return Unpickler(prev_Scr).load()

    except EOFError : 

        return dict() 

I have encountered this error many times and it always occurs because after writing into the file, I didn't close it. If we don't close the file the content stays in the buffer and the file stays empty. To save the content into the file, either file should be closed or file_object should go out of scope.

That's why at the time of loading it's giving the ran out of input error because the file is empty. So you have two options :

1. file_object.close()
2. file_object.flush(): if you don't wanna close your file in between the program, you can use the flush() function as it will forcefully move the content from the buffer to the file.