Caveat, Caveat (Warning, Warning) I know I've been quite busy with other activities, and ITMT my client status went really bad and even worse reached its final point and self-rebooted while I was trying to suspend it, but anyway this update is needed because I just discovered that my last choice to prepend %ProgramFiles(x86)%\Gpg4win\bin;%ProgramFiles(x86)%\GnuPG\bin;%PATH% was not very good. Why ? Simple, as I discovered today (few hours ago) using this syntax, will only be valid&useful only if you really want to restrict Gpg4win v3.1.16 usage only to accounts in Administrators group.
Ok, so now you're wondering: How I discovered this effect ? Again simple, desktop shortcut that I have for starting new 'Command Prompt' was modified to always run as Admin, so I have to specifically choose when I want to run it without Admin privileges, and so today, after I didn't notice I had launched Kleopatra before, right after closing it, I launched a new Command Prompt and so when I tried to run 'gpgconf --kill gpg-agent' I only received this answer :

'gpgconf' is not recognized as an internal or external command,
operable program or batch file.

So then I obviously opened another 'Command Prompt' as an Admin and correctly killed gpg-agent so ensuring that everything was indeed still working as expected.
So now you're asking, why in the past I had confirmed that prepending those paths I was expecting to work, really worked ?
If you remember well how I reported Iìve done my past installations and tests, I also made those changes in OS System Environment Variables really on the fly and then just re-confirmed they were valid via GUI by simply pressing [ OK ].
And so this is the test I just repeated again and so I can re-confirm you that only after by doing so, every new 'Command Prompt' started as non Admin user will have proper access to those newly prepended paths.
Otherwise, those paths will work only for any new 'Command Prompt' if run with an account in Administrators group.
So while this can still be temporarily fine for me, I'm unsure it might have been a real standard choice for Gpg4win v3.1.16 setup run without experiencing the error I'm reporting in this bug, so please just ensure to avoid using %ProgramFiles(x86)%\Gpg4win\bin;%ProgramFiles(x86)%\GnuPG\bin; syntax when changing your paths on the fly by prepending it or appending to %PATH% even if you should try to definitely solve same error I found and reported with this bug. OK ?
Thanks for your attention (for now).

Just adding this note because a next step I'm also evaluating in my current T5593 configuration status it to temporarily create a new Gpg4win 3.1.16 hybrid configuration by also adding latest GnuPG v2.2.31 to see if all issues I reported here are still present (which is also quite probable).
Also because of T5593 it would just be quite interesting to see if GnuPG v2.2.31 too might experience same T5593 path related error.

Hi Werner,

Just tracking my own additional investigation still about past Werner statement "percent escaping is correct and required" when this bug was closed for 1st time.
Also found interesting past references into rG055f8854d3f4 and rGe064c75b08a5 but only this last seems indeed much more specifically directly involved since it really contains related part of code (common/stringhelp.c) directly involved with this bug report for 'percent escaping' ':' (colon) character with '%3a' string even if sometimes, when possibly un-needlingly done, may even provide users unexpected on-screen displayed results like those I documented in this bug.
Problem now is that to really fully understand why on-screen displayed strings by 'gpgconf --list-dirs' correctly show a ':' (colon) correctly expected character near an unexpected (by end users) '%3a' (percent escaped) string that should just have corresponded with another simple (& user correctly expected) ':' colon character I can only really see to 2 options:
A) reopening this bug once again :-S ;
B) simply opening a new separate one asking for some additional explanations and maybe even to consider some future slight code changes to (at least for Windows OSes) ensure 'gpgconf --list-dirs' directory displayed paths results are more UI consistent with 'gpgconf --list-dirs homedir' or 'gpgconf --list-dirs sysconfdir' displayed ones where displayed C:\... paths always correctly display ':' (colon) instead of '%3a'.
So far this last seems me best viable option also because in same rGe064c75b08a5 I also saw another piece of code (tools/gpgconf-comp.c) with some similar code lines, that apparently (it seems me) if directly referenced (at least only for Windows OSes only, so maybe when a system variable %OS%==Windows_NT exists) instead of current one (common/stringhelp.c) also providing '%3a' 'percent escaping' results, might then have probably also easily avoided '%3a' user unexpected on-screen displayed results only depending by 'percent escaping'.

Just adding this note for any future reference needs only (or even message localization reference, since involved text characters strings are also expected to be among Italian language localized messages even if involved strings are not specifically being localized).

Hello again Werner,

Hello again Werner,

OK, effect avoided. Only dued to a big sequence of '-' characters that this bug reporting system interpreted as special control code characters for making font bigger.

As I anticipated here's screenshot I also saved.
P.S. Just in case you might wonder why I tried to execute 'man' not existing command is because I also incorrectly tried to run it 2 days ago when after I tested some GnuPG commands in a CMD window, and again same window self-closed with no error messages or any dump creation and again I'm sure at that time I didn't run 'mode con' before those GnuPG commands (I'm unsure which ones but they probably some were the same I also already reported here). Please also note that making 'Stato del dispositivo CON:' so big was unintended and very likely just an effect of cut & paste I did, so now I'll try to see if I can avoid that effect.

Hello again Werner,

Ok, but the problem is that by default CMD command windows do not use any Unicode set of characters, and their default font is 'Raster characters' and the typical display of characters inside these windows, at least for Italian people because this was the default since MS-DOS age, is to only consider using MS-DOS ASCII codepage 850, not Unicode.
And this is also why before showing the error message I ran the command mode.
Anyway because of the 2 characters getting displayed instead of single expected 'è' (whose character code is 0x82) I can also tell you that by using Charmap.exe again (just in case you may not know it allows display of any Unicode or Raster font characters and their hexadecimal codes) and so switching its default font from System (Unicode) to 8514oem (raster, corresponding to 8514oem.fon) I've been able to determine which should be the 2 wrong displayed characters hexadecimal codes : 'Ã' (0xC3), and '¨' (0xA8) but here obviously both characters cannot be represented correctly because this site is using 'Segoe UI' font, which is Unicode too.
So the only main way to check that I identified the correct characters will be if you (or someone else you know) with another Windows client run Charmap.exe switch font to 8514oem (raster) and check that displayed characters corresponding to 0xC3 and 0xA8 are the same that got displayed in the error message bitmap I provided (a part from probably being able to find where in Italian messages localization rather then in source code those 2 characters have been used incorrectly).
P.S. Because in a past similar bug about Italian localization I saw a comment from you about this kind of option, please just let me know in case you think I might possibly be able to help you to review involved 'GPG' Italian error message(s) for this bug.

Hello Werner,

P.S. Also note that my Gpg4win 3.1.16 installation status is still last T5593 described one.

Here's the file I anticipated (this time uploading worked... :-D ) (my Gpg4win 3.1.16 installation status is still T5593 described one).

Could anyone please be so kind to confirm me if when 'gpg4win-3.1.16.exe' setup completes without any error the new folders where Gpg4win and GnuPG commands can be found are prepended (so inserted at beginning) or appended (so added at the end) of already existing %PATH%) ?
I'm asking this to properly ensure that my new manually modified configuration %PATH% is indeed equivalent to an original configured one (and so far I've assumed that my manual changes should have been prepended %ProgramFiles(x86)%\Gpg4win\bin;%ProgramFiles(x86)%\GnuPG\bin;%PATH% but doing this was probably only my choice because such changes were just faster to do).

@grv87, thanks for clarification (and very interesting side thread reference you gave, indeed, also because it also gives you an idea of how system environment changes during OS startup). I precisely see your point and that's also why I said "create 2 new system variables".
I've not said this very explicitly before but for that I also meant to just create them during Gpg4win setup. When it is run, I assume we can also say that OS system environment is already in place and %PATH% should already be stable enough to consider that as a good starting point to add things. So once you can really do that (I mean add 2 new system variables), and then also ensure they're created correctly, then I can also assume that then starting to use them to update %PATH% system variable might be fine too.

@grv87 OK, many thanks indeed for confirming all this.
About your 1st comment: that's just right why I asked about it. Regarding md5sum and pinentry both must be the reason why now they decided to also add 1st path into environment while in older version wasn't there. Main issue is that because of the quite generic 'PATH env variable too big' error so far we can only assume 2047 was indeed maximum size for %PATH% Gpg4win developers have been expecting so far, while after that change from March 2012 QFE fix a definitive fix to implement in setup and rest of Gpg4win involved code will just be to enhance that maximum allowed path size to 4095 characters (BTW also checking anyway for size of %PATH% already active before setup will continue with new %PATH% changes is probably best option too).
About your 2nd & 3rd comments: thanks for those useful references. Would probably be quicker to implement, but it's still again true that maximum size expected for %PATH% will still need to increment from (likely) 2047 to 4095, plus also what you said about something "for expert users only". And even then inside README.txt (that now corresponds to %ProgramFiles(x86)%\GnuPG\README.txt or %ProgramFiles(x86)%\Gpg4win\share\gpg4win\README.en.txt or %ProgramFiles(x86)%\Gpg4win\share\gpg4win\README.it.txt) there should be at least 1 note about suggested way to do things. Problem is that because of above (March 2012) MS KB article statements '... If an existing value contains more than 2047 characters, you cannot enter additional data. However, you can delete the characters that are displayed. ...' whenever %PATH% size is over that value (always true for me even after manual %PATH% downsizing I had to do) OS UI will be of no or very little help (and by very little I intend that to overcome that OS UI limitation expert users with Admin privileges will 1st need to manually modify Path value into Registry, let's say by adding at least 1 or 2 ";" really unneeded, then just use OS UI to modify %PATH% system variable by deleting those ";" unneeded (i.e. %ProgramFiles(x86)%\Gpg4win\bin;;%ProgramFiles(x86)%\GnuPG\bin;;) and then once removed confirm with OK twice, and voilà it's done).
(P.S. BTW I just checked that so it really works fine for all applications started after that change ;-D so this might probably be best known option to document inside that README.txt.
N.B. JFYI in the past I also tried to use SETX from command line, and so I discovered that it only has a 1024 maximum characters limit after which it will just truncate any expected change that is saved anyway into selected system variable).
Otherwise, another possible approach variation but unsure if needing more coding would be to create 2 new system variables (let's say Gpg4win and GnuPG) and then add both %Gpg4win%;%GnuPG%; in front of existing %PATH% while installing, but obviously still after enhancing maximum allowed PATH size to 4095.

While I'm still waiting for anyone to possibly answer my last 'Sat, Sep 18, 6:29 PM' question I've also added there the explanation behind that question... :-)

OK, while I'll be awaiting for anyone to possibly answer my last T5593 'Sat, Sep 18, 6:29 PM' question, just for sake of completeness I've also been able to check that inside registry (HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Gpg4win\kleopatra\Capabilities) Kleopatra icon has correct expected value so ApplicationIcon (REG_SZ) = 'C:\Program Files (x86)\Gpg4win\bin\kleopatra.exe,0' (N.B. preceding text string into registry is obviously unquoted ). ;-D

OK, while I'll be awaiting for anyone to possibly answer my last 'Sat, Sep 18, 6:29 PM' question that I decided to re-update today, just for sake of completeness I've also been able to check more inside registry but details will only go inside T5605 since only pertinent there ;-D

Because of T3458 and other references to PATH I found in the past (see past references I added previously into this bug), could anyone please be so kind to confirm me if am I right to assume that under normal conditions (so with no PATH related errors like 'PATH env variable too big' I reported here) after proper end of 'gpg4win-3.1.16.exe' installation only following (unquoted) path string 'C:\Program Files (x86)\Gpg4win\bin;' would have been added at beginning of PATH system environment variable ?
Or if not, would new path rather have 'C:\Program Files (x86)\Gpg4win\bin;C:\Program Files (x86)\GnuPG\bin;' (always unquoted) prepended at beginning of PATH system environment variable ?
P.S. Please note that I'm only asking this to then try to properly manually set PATH system environment variable accordingly and then see if my (current) 2nd 'gpg4win-3.1.16.exe' installation can still work correctly as expected or not... ;-D

Woops, I also forgot to say that only Kleopatra icon I found on my desktop has this problem. Original folder path of Kleopatra.lnk shortcut I have on my Desktop is C:\Users\Public\Desktop.
While 'Kleopatra.lnk_' I uploaded after renaming its extension as 'lnk_' was just another copy of it I temporarily put on my own Desktop only for uploading.

Woops, :-s I forgot to also add all these details from additional investigations I already did (obviously assuming it might be helpful ones for definitely fixing issue I reported (and my apologies in advance for whom might find lenght of all this really excessive, 8-) since I simply tried to comprehensively summarize results...)

My apologies for further delay before also providing this screenshot bitmap of error found (because of initially not finding specific site info about best browser to use and not seeing 'cloud symbol' (many thanks werner :-D ) I obviously had to switch from IE11 to MSEdge and then also manually import proper cookies needed for this site :-(( )

Apologies for my (newbie) comment on this bug reporting system. Since I have a screen shot bitmap better showing error I described, could anyone tell me how to attach to this bug ?