Title: Python 3.5.1 installer fails on Windows 7
Type: Stage: resolved
Components: Windows Versions: Python 3.5
Status: closed Resolution: out of date
Dependencies: Superseder: Change Windows install to applocal UCRT
View: 32507
Assigned To: Nosy List: eryksun, nedbat, paul.moore, steve.dower, tim.golden, zach.ware
Priority: normal Keywords:

Created on 2015-12-26 03:27 by nedbat, last changed 2018-01-06 23:59 by steve.dower. This issue is now closed.

File name Uploaded Description Edit
Python 3.5.1 nedbat, 2015-12-26 03:27
Python 3.5.1 more nedbat, 2015-12-27 10:34
Messages (9)
msg257017 - (view) Author: Ned Batchelder (nedbat) * (Python triager) Date: 2015-12-26 03:27
I tried to install 3.5.1 32-bit into a fresh virtualbox image from (IE 10 on Win 7), and got this error message.  When I try to run Python with "py -3", it will not run, it only shows:

                    python.exe - System Error
                    The program can't start because api-ms-win-crt-runtime-l1-1-0.dll is missing from your computer. Try reinstalling the program to fix this problem. 

I tried repairing the installation (with the control panel), which did not help.

I've attached the log files created by the installer.
msg257019 - (view) Author: Eryk Sun (eryksun) * (Python triager) Date: 2015-12-26 07:37
The main log file reports that installing the CRT exited with the code ERROR_INSTALL_ALREADY_RUNNING (0x652): 

    Another installation is already in progress. 
    Complete that installation before proceeding 
    with this install.

You may need to completely reinstall to have it retry installing the CRT update.
msg257031 - (view) Author: Ned Batchelder (nedbat) * (Python triager) Date: 2015-12-26 13:07
This was my second attempt, and there is no other installation running.
msg257035 - (view) Author: Ned Batchelder (nedbat) * (Python triager) Date: 2015-12-26 14:20
This is in a virtualbox. I have my host OS files mapped in the guest Windows OS to drive N:.   When I try to install by running N:\Downloads\python-3.5.1.exe, it fails with the error shown above.  When I copy the file to the C: drive, it succeeds! ?
msg257041 - (view) Author: Eryk Sun (eryksun) * (Python triager) Date: 2015-12-26 17:16
Packages are installed from the ProgramData folder on the system volume. For example, the log shows the CRT update executed as follows:

    "C:\Windows\system32\wusa.exe" "C:\ProgramData\Package Cache\
    Windows6.1-KB2999226-x86.msu" /quiet /norestart

Is it installing from the same ProgramData directory when it succeeds?
msg257068 - (view) Author: Ned Batchelder (nedbat) * (Python triager) Date: 2015-12-27 10:34
I'm attaching another bunch of logs.  There seem to be two installations here, one of which succeeded.
msg258412 - (view) Author: Steve Dower (steve.dower) * (Python committer) Date: 2016-01-16 21:15
Sorry for letting this slide for a while...

Can you check (in Programs and Features, View Installed Updates) whether you have KB2999226 installed? If not, you can get it from

In the first install, this component failed (hence the missing DLL error), and then in subsequent installs it wasn't re-run. I'm not sure exactly what happened here, but it's possible that the installation was deferred until the next reboot automatically. Being a Windows Update, we don't have much control over how these are managed and the operating system can basically do what it likes.
msg258465 - (view) Author: Ned Batchelder (nedbat) * (Python triager) Date: 2016-01-17 12:27
Steve, I do have that update installed.
msg258471 - (view) Author: Steve Dower (steve.dower) * (Python committer) Date: 2016-01-17 14:32
Is your installation working okay then? You seemed to imply that in an earlier message, but I just want to confirm before closing the issue.
Date User Action Args
2018-01-06 23:59:26steve.dowersetstatus: open -> closed
superseder: Change Windows install to applocal UCRT
resolution: out of date
stage: resolved
2016-01-17 14:32:46steve.dowersetmessages: + msg258471
2016-01-17 12:27:45nedbatsetmessages: + msg258465
2016-01-16 21:15:41steve.dowersetmessages: + msg258412
2015-12-27 10:34:04nedbatsetfiles: + Python 3.5.1 more

messages: + msg257068
2015-12-26 17:16:58eryksunsetmessages: + msg257041
2015-12-26 14:20:17nedbatsetmessages: + msg257035
2015-12-26 13:07:47nedbatsetmessages: + msg257031
2015-12-26 07:37:22eryksunsetnosy: + eryksun
messages: + msg257019
2015-12-26 03:27:22nedbatcreate