ValueError: 不支持 pickle 协议: 3，python2 pickle 无法加载被 python3 pickle 转储的文件？

我使用 pickle 转储 python3上的文件，并使用 pickle 加载 python2上的文件，ValueError 出现。

那么，python2 pickle 不能加载被 python3 pickle 转储的文件吗？

如果我想要? 怎么办？

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最佳答案

You should write the pickled data with a lower protocol number in Python 3. Python 3 introduced a new protocol with the number 3 (and uses it as default), so switch back to a value of 2 which can be read by Python 2.

Check the protocolparameter in pickle.dump. Your resulting code will look like this.

pickle.dump(your_object, your_file, protocol=2)

There is no protocolparameter in pickle.load because pickle can determine the protocol from the file.

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Pickle uses different protocols to convert your data to a binary stream.

In python 2 there are 3 different protocols (0, 1, 2) and the default is 0.
In python 3 there are 5 different protocols (0, 1, 2, 3, 4) and the default is 3.

You must specify in python 3 a protocol lower than 3 in order to be able to load the data in python 2. You can specify the protocol parameter when invoking pickle.dump.