Patch Problems ...

I want the Doom 2 v1.7a version, but when I try to install the patch, I get an error called "ept0036 Old File not found. However, a file of the same name was found. No update done since file contents do not match." it says. How can I fix this? I'm tired of trying many times it just doesn't work. Any help that works will be appriciated.

You might have a wrong Doom version. What version is your starting point? 
Run Doom2.exe in Dosbox and see the version number briefly appear on the 1st screen. Then either:

downgrade 1.9 to 1.666:
https://www.doomworld.com/idgames/utils/exe_edit/dm2dwngr

update 1.666 to 1.7a:
https://www.doomworld.com/idgames/idstuff/doom2/doom2p16

update 1.7 to 1.7a:
https://www.doomworld.com/idgames/idstuff/doom2/doom2p17

update 1.8 to 1.9:
https://www.doomworld.com/idgames/idstuff/doom2/d2_18_19

I have Doom 2 v1.666 and I am using the Doom 2 v1.666 to v1.7a patch but it says what is up there. I read the forums it says only works with v1.666 dated 30-08-1994 but where can I get that?

Dunno if it is actually that but seems like no files around the whole internet I think, It'll be appriciated if you give me the already patched version :)

We don't give out full copies of Doom 2. Maybe try this patch which is for 29-8-1994 or 20-9-1994.

Hey Ichor, the one you gave me doesn't work either. I tried this one before. It never worked. I bought the game on 6 November 1994

I played it in a Windows 3.1 machine and it said my version was v1.666. I used a deice.exe to install the game. Today, I got the files from the old pc to my newest one and I installed it the same way on DOSBox v0.74. It says v1.666 when I launch the game but the patches still doesn't work. One thing I had noticed was the installation files said they were dated 30-9-1994. I don't know where I can get a 29-8-1994 or 20-09-1994 version of Doom 2 v1.666. I can give you the installation files of my Doom 2 copy so you install and test all the patches on it that you know. I hope you find what is wrong :D

Before:

DOOM2.EXE
Size: 670.90KB (687001B)
MD5: 22e3fc7854f030df977d26faf1e342be

DOOM2.WAD
Size: 14.25MB (14943400B)
MD5: 30e3c2d0350b67bfbf47271970b74b2f

After:

DOOM2.EXE
Size: 670.90KB (686997B)
MD5: 3de58b8f768e990856764df982ad5043

DOOM2.WAD
Size: 13.94MB (14612688B)
MD5: d7a07e5d3f4625074312bc299d7ed33f

The patch posted below works for me, even if DosBox won’t keep any timestamp of any file. So I guess your files may be somehow corrupted or accidentally modified.

https://www.doomworld.com/files/file/7025-aaa/

You said the latest date is 24-12-1996 (or December 24, 1996), which means that it's been changed somehow.

24-12-1996 (DD-MM-YYYY)? And the hour is 23:32 (GMT +1)? Very likely, that means this file has been repacked using TorrentZIP. It sets this arbitrary timestamp to repack ZIP archives deterministically.

Only thing I need is the v1.7a Doom2.exe overall I can use any other Doom2.wad file

https://github.com/Doom-Utils/iwad-patches/tree/master/vanilla-engine

Thank you so much, this is what I've been looking for 4 years and It's finally solved! :DDDD

I've set up a website covering this many years ago, but it is not as complete as chungy's github...

http://www.doomgate.de/files/duub/index.html

You don't see it too often any more, but this issue is typically indicative of using a warez copy of the game.  As I recall the story goes that someone got their hands on a leak of v1.666 that was slightly earlier than the official release, circulated it, and it became a fairly popularly exchanged version in pirate circles.  The official patch doesn't patch it because it wasn't an officially sanctioned release and id had no desire to support it given the circumstances.

On 2017/12/17 at 6:13 PM, ETTiNGRiNDER said:

You don't see it too often any more, but this issue is typically indicative of using a warez copy of the game.  As I recall the story goes that someone got their hands on a leak of v1.666 that was slightly earlier than the official release, circulated it, and it became a fairly popularly exchanged version in pirate circles.  The official patch doesn't patch it because it wasn't an officially sanctioned release and id had no desire to support it given the circumstances.

http://web.archive.org/web/20170113203139/http://www.doomworld.com/classicdoom/info/patches.php

Quote

doom2p.zip 148 KB

Doom2 v1.666 (dated 8-24-94 or 9-20-94) and Doom2 v1.7 (dated 9-21-94) to Doom2 v1.7a.

 

Note: there is -no- patch for Doom2 v1.666 dated 8/25/94. This version has been declared "pirated" by id Software and is no longer supported.

And the reason I use wayback machine link because actual link just 404ed since May, 2017.

Doomwiki.org's Doom2.WAD has no such pirate version info anymore when someone with IP address on 2009 decided to remove it and said it was Doomworld's mistake.

I wonder if change the file date of Doom2.wad to 8-29-94/8-30-94 would still patchable, if filesize and MD5 string still right?

The WAD might be the same, but what about the EXE?  Does it abort patching if that doesn't match a hash?

43 minutes ago, ETTiNGRiNDER said:

The WAD might be the same, but what about the EXE?  Does it abort patching if that doesn't match a hash?

Yes, DOOM2.EXE is different, so it won't patch...

https://doomwiki.org/wiki/DOOM2.EXE#Older_versions

I just forgot about EXE and maybe some other files.

There was an option to skip missing files so the patch should work. But you don't need to use those DOS patches anyway. There's an unofficial patch to generate any iwad version from 1.9 but i don't remember where it is right now.

http://doomgate.de/files/duub/index.html

Chungy also has made a complete archive on github of all iwad-diff's:

https://github.com/Doom-Utils/iwad-patches

And YES, RTP can skip missing files:

    PATCH  Version 2.11 - .RTPatch(R) Professional - Software Update System
                            DOS and Windows Edition
       (C) Copyright Pocket Soft, Inc., 1991-1994.  All Rights Reserved.

Syntax  :  PATCH [<Options>] [<Update Directory> [<Patch File Name>]]

Options : -BACKUP[:<Directory>]
          -ERRORFILE
          -FILE:<Filename>
          -HELP
          -CONFIRM
          -D
          -IGNOREMISSING
          -LIST
          -MESSAGE
          -NOBACKUP
          -NOCONFIRM
          -NOERRORFILE
          -NOIGNOREMISSING
          -NOMESSAGE
          -NOPATHSEARCH
          -NOSUBDIRSEARCH
          -NOUNDO
          -NOXTRAMEMORY
          -PATHSEARCH
          -QUIET
          -SUBDIRSEARCH
          -UNDO
          -VERBOSE
          -XTRAMEMORY

I knew Romero had said something more about the circumstances behind the pirate v1.666 somewhere, turns out it was together with the "sound dork" rant:

https://groups.google.com/forum/#!original/alt.games.doom/THy47aVcHLI/Pdbt3GZpBV0J

It's really sad that the Doom 2 1.666 is pirated and dristibuted everywhere.