Python fromtimestamp OSError

Question

For some reason when constructing datetimes using fromtimestamp, I get a "OSError [Errno22] Invalid Argument" when I use negative times less than -43200 (-12hrs). I am on Win7 64-bit and python 3.5.1. Here's code that produces the error.

>>> import datetime >>> import pytz >>> datetime.datetime.fromtimestamp(-43200, pytz.utc) datetime.datetime(1969, 12, 31, 12, 0, tzinfo=<UTC>) >>> datetime.datetime.fromtimestamp(-43201, pytz.utc) Traceback (most recent call last):   File "<stdin>", line 1, in <module> OSError: [Errno 22] Invalid argument 

The sample uses pytz to simplify timezone information, but the error also occurs without it.

Answer 1

If you get this error and you're not using an obviously wrong timestamp, check your units.

fromtimestamp expects a timestamp in seconds, whereas it's quite common to get timetstamps in milliseconds (e.g. I found this when trying to parse a timestamp produced from Moment.js in a calendar widget).

Take the timestamp 1523443804214 - it's 11th April 2018, about 15 minutes before I made this post. According to Epoch Converter, no problem, but note: "Assuming that this timestamp is in milliseconds:".

In Python this returns an OSError:

In [15]: datetime.fromtimestamp(1523443804214.0) --------------------------------------------------------------------------- OSError Traceback (most recent call last) <ipython-input-15-0c8efd251031> in <module>() ----> 1 datetime.fromtimestamp(1523443804214.0) 

However if we divide by a thousand:

In [17]: datetime.fromtimestamp(1523443804.214) Out[17]: datetime.datetime(2018, 4, 11, 11, 50, 4, 214000) 

the result is what we expect.

Answer 2

If the timestamp is out of the range of values supported by the platform C localtime() or gmtime() functions, datetime.fromtimestamp() may raise an exception like you're seeing.

On Windows platform, this range can sometimes be restricted to years in 1970 through 2038. I have never seen this problem on a Linux system.

If you have a negative timestamp t on Windows and are encountering this error, here is a workaround:

from datetime import datetime, timedelta datetime.fromtimestamp(0) + timedelta(seconds=t)     # localtime datetime.utcfromtimestamp(0) + timedelta(seconds=t)  # utc