[Reader][Win7] 21208 update breaks Acrobat Reader, won't start, missing dll

New update post:  3/5/2026  1630

Yesterday I updated Reader to 2025.001.21265 on Computer One (Dell M2800, Win 7 Pro) which also has loaded on it SumatraPDF, FoxitPDF and Firefox (please remember these).  

A quick summary of the steps on Computer One is:  1)  put missing api..dll’s in appropriate System folders (as per HelpfulJohn).  2)  Downloaded and installed 2025.001.21223  3)  Use Adobe to open pdf.  Open correctly.  4)  After a while Adobe updated itself to 2025.001.21265.  5) disabled api….dll’s (changed names) in Systems files - Reader still worked.

Adobe behaved correctly:   1)  No “missing api...dll” message   2) No (not one) error message about WinHttpWebSocketCompleteUpgrade missing from dynamic link library WINHTTP.dll   3)  Using “Open With” to open a pdf, all four PDF readers listed above were shown as available, and they were all in the Windows Default Programs list for selecting default program to open pdf files.

Everything seemed to work as it should for Computer One.

---------------------------------

Today I updated Reader to 2025.001.21265 on Computer Two (Dell E6520, Win 7 Pro) - different story:

To do this update I removed Reader Version 22.003.20282, earlier suggested by one participant as working on Windows 7.  It had only kinda-worked for me (several issues).  You may have some other older version  installed - it doesn’t matter.

Steps:  1)  Downloaded 21223 install file from site given by Helpful John.  2)  Downloaded Acrobat Cleaner tool from https://www.adobe.com/devnet-docs/acrobatetk/tools/Labs/cleaner.html.  3)  Used Windows Programs and Features to uninstall older Reader (DO THIS FIRST), then Cleaner tool to remove all traces of old installation.  4)  Put each api….dll into appropriate System folder.    5)  Re-boot computer [precaution only].  6)  Install 21223 from executable . 7)  Download from https://www.adobe.com/devnet-docs/acrobatetk/tools/ReleaseNotesDC/continuous/dccontinuousmar2026.html#dccontinuousmartwentytwentysix   the 32-bit update file AcroRdrDCUpd2500121265.msp.   I believe (but am not sure) that this file will only update 2025.001.21223.  Click to install.  You should now have a “working” Version 21265.

BUT…. for Computer Two:  1)  when I opened a pdf using the 21265 updated file, I still got the error message about WinHttpWebSocketCompleteUpgrade missing from dynamic link library WINHTTP.dll .  Clicked OK three times to make it go away.  It kept coming back at random times  2)  SumatraPDR and Foxit no longer appeared in the “Open With” option list, nor did they appear in the Default Programs list for pdf files.  I had to uninstall/install SumatraPDF to get it back in the list.  On another computer with updated 21265 Adobe, Sumatra and Firefox pdf options (but not Foxit), Sumatra and Firefox went away from the lists. 

IMHO Adobe has not fully fixed the 32-bit Reader (still get the  WinHttp..Upgrade...HINHTTP.dll error message - randomly, on some of my computers but apparently not on others - and the disruption of “Open With” options).  I have no confidence in Adobe Reader despite Adobe’s effort to fix it.  For now I will use SumatraPDF.  It does not all the fancy features of Adobe, but it seems to correctly open, read and print the pdf files I tested it with.  And...it uses a fraction of the computer resources that Adobe uses.  Firefox has a problem printing pdf files which look correct on the screen but do not properly fit the page when printed.  I reported this to Mozilla a couple of days ago, and from the response I got they are looking at it.  We’ll see.

I hope my experience is of some help.  I want to thank HelpfulJohn for the effort he has put into this issue.

How do I fix Acrobat Reader error on Win 7: “api-ms-win-core-winrt-I1-1-0.dll is missing from your computer” in detail?
Everyone keeps saying open Reader and check for updates but it will NOT OPEN because of the missing .dll!

Can anyone please give a detailed answer on what to do?

Do I uninstall Reader or not?

Please post the link to install the update and name the update please because there are four of them in the list.

Thank you if anyone will take the time to post a detailed reply.

Hola AnandSri:  resulta que cuando empezaron todos los problemas, desinstalé el programa para poder comenzar todo desde el principio correctamente con la actualización.

He estado esperando respuesta para que se lanzara la actualización que indicas y por tanto ahora no puedo entrar a instalar la actualización, porque resulta que cuando intento instalar el programa Adobe Acrobat reader, sale un mensaje de error (W64 bits): se interrumpe, “codigo de error 150201” con lo que si no puedo instalar el programa, no puedo descargar la actualización y no puedo utilizar.

¿podrías ayudarme por favor?

Muy agradecido

I had a similar experience to that just described by HelpfulJohn.  Yesterday (3/3), on my “test” computer with the api...dll’s installed in the System folders, I opened Version 25.001.21223.  It seemed to work, and I did not get the error message described by Antoniusll which I had gotten earlier in the day.  After a few minutes, an “Update” pop-up box appeared.  I accepted.  The box stayed, and stayed and stayed - never closed, or said “update completed.”  I eventually closed Adobe, and re-opened it.  It now said Version 25.001.21265.  I closed it, disabled the api...dll’s , and re-opened.  It worked.  To my happy surprise, it was still working this morning in multiple teste.  I have not YET gotten the error described by Antoniiusll.

But, as noted by a couple of participants, unless you can open 25.001.21223 (which requires api….dll placed in the C:\Windows\SysWOW64 folder), it won’t auto-update.  Catch-22.

There is another (manual) update method described by AnandSri.  I have not tried this method.  Go to:  

 https://www.adobe.com/devnet-docs/acrobatetk/tools/ReleaseNotesDC/continuous/dccontinuousmar2026.html#dccontinuousmartwentytwentysix

There you will find several .msp files.  For those not familiar with .msp files (and I was not until now) these are Microsoft Installer Patch files.  They are supposed to work like .exe files (click to execute), but will only update already-installed files.  The one which seemed most appropriate to update 32-bit Version 25.001.21223 is AcroRdrDCUpd2500121265.msp. 

I have three “work” Win 7 computers to “fix”.  All have broken Version 225.001.21223 without the api...dll files added to the System folders. I may try the .msp update method on one.  If it works, I’ll do the same on the others.  If not, I’ll put the api...dll files in the system folders as a temporary solution, and hope that the auto-update works.

04/03/26 15:55

The instructions provided by Adobe Community Managers are not clear.

For those of you who are still having Acrobat problems this may help you.

In order to successfully install the latest version 25.001.21265 you may need to install the older version 25.001.21223 first. And to get that working download the missing dll file it needs.

You should then be able to start Acrobat, and then manually perform an update to get version 25.001.21265.

I have just done this myself and it worked for me.

This is what I did over the past few days.

1. Uninstall version 25.001.21223 and then re-install it again.

If you already have version 25.001.21223, then just go to step 3.

2. Install version 25.001.21223 from here:

https://get.adobe.com/reader/enterprise

Select Windows 7 and English (UK)

There is only one version

Reader 2025.001.21223 English UK for Windows (32 bit)

I have not used the other installing website links mentioned by Community Managers.

3. To get the missing dll file follow these steps:

4. Go to this website

https://www.dllme.com/dll/files/api-ms-win-core-winrt-l1-1-0

5. Scroll down and click on the large DOWNLOAD (in pink)

(Ignore any of the Ads that appear – don’t click on them)

(Ignore anything that says ‘Click to Continue’ – these are ads)

6. Acrobat Reader is 32 bit, so you only need to download the 32 bit one

7. Get the 32 bit version

Many different versions of the file are shown (most have same version number)

Scroll down and locate the x86 - 32 Bit one (the first one for version 10.0.9904.0 will do,

OR BETTER STILL the one which states this is middle column:

SHA256: 4fb6b6b759a6d9184b8d032bad76516ca8539c6102de02bc1e8de568bb

)

Click on DETAILS (in pink), and then START DOWNLOAD (in pink)

8. This file will be in your explorer downloads folder

api-ms-win-core-winrt-l1-1-0_x86

It’s a zipped file so double click on it and explorer will unzip it

9. On a pc that is 64 bit cpu:

You WILL have folder SysWOW64

Copy the file shown api-ms-win-core-winrt-l1-1-0.dll

to C:\Windows\SysWOW64

10. On a pc that is 32 bit cpu:

You will NOT have folder SysWOW64

Copy the file shown api-ms-win-core-winrt-l1-1-0.dll

to C:\Windows\System32

11. Once file has been copied, just start Acrobat Reader. No need to restart first.

12. Start Acrobat and update to latest version 25.001.21265 by doing this:

At top left select

Menu > Help > Check for Updates

It will show ‘Update is available’ and ‘Updating Adobe Acrobat Reader (25.001.21223)’, which is the version currently installed.

Click on ‘Download and Install’ which will take a few minutes.

It will probably tell you to ‘Close programs in use’. So just shut down Acrobat that is running, and then click ‘Retry’.

Hopefully it will successfully install version 25.001.21265

Just start Acrobat. I did not need to restart my pc.

Downloaded and tried to install but am told fix cannot run as my installed version is not right. I’ve just re-installed v 25.001.21223 on Windows 7. Also you say “ by navigating to Menu > Help> Check for Updates” but that’s impossible as you can’t open Reader in the first place.

Hello,

No matter what do (I’ve tried all those fixes mentioned below), I’m still getting
the application was unable to start correctly 0xc00007b
This has been a frustrating experience over the past two weeks.

Dirk

Trying to reply here - getting message “Somethings gone wrong”.

Hi,

I have Acrobat Reader 32-bit, Win 7 SP1 64-bit

I’ve uninstalled the flawed Adobe Acrobat Reader and re-installed the latest version I’ve found on the Adobe download site. It’s still the one ending in 21223. Even after re-starting my machine, I’m still getting the same error:
The application was unable to start correctly 0xc00007b.
I subsequently tried installing the patches, first this one: AcrobatDCx64Upd2500121265.msp  then AcrobatDCUpd2500121265.msp
During installation, I get the message - unable to install as this is not linked to any program.
The app actually did update automatically yesterday but the The application was unable to start correctly 0xc00007b error came up as well. After reading all these messages here and losing many hours in the past few weeks, I still don’t have a functioning AAReader app and am very frustrated. What am I doing wrong?
Thank you,
Dirk