You are right. I saw everything else, but I did not see that Windows 7 does not meet the minimum requirements for adding a second language in an iso file. Is that why there are so many errors?!
Check log files inside C:\Windows\Logs\DISM you may need to run these command on your Win7 Code: copy /y %SystemRoot%\System32\slc.dll %SystemRoot%\System32\ext-ms-win-security-slc-l1-1-0.dll copy /y %SystemRoot%\SysWOW64\slc.dll %SystemRoot%\SysWOW64\ext-ms-win-security-slc-l1-1-0.dll you don'e need LP.esd file if you already provided LP.cab file
Although the errors are again the same as in the picture I uploaded in my comment from the previous page, I followed your advice with this code you wrote and the newly created iso is: 19044.1288.211006-0319.21H2_RELEASE_SVC_PROD1_CLIENT_X64FRE_EN_BG.iso - with 420 MB is more-small from the original base en-us_windows_10_iot_enterprise_ltsc_2021_x64_dvd_257ad90f.iso. I burned the new iso to a flash drive just to check if the start screen would present an option to choose an installation between English and the second added language. Indeed this choice was shown and when the second language was selected the installation was entirely in the added language. It's getting late and I don't have time to complete the installation. This is my second attempt to add a language to an iso file and it turned out to be successful. Question: Should I be worried about something that the errors in the script are again the same - as in the picture on the front page? Although the new iso has the second language correctly added. I would even ask you to update the script with those commands you wrote in your previous comment. It's really nice to have the option through Windows 7 (to cover minimal hacking) to be able (officially via your script) to build Windows 10 with the addition of a second language. Or this code you wrote, add it to the script, because your opinion, which contains this code, will be far behind in this thread and... On the other hand - it is logical that through Windows 7 it is possible to create an iso with added second language - as a springboard for Windows 10 (From Windows 7 to migrate to Windows 10). Since I have no idea what to look at C:\Windows\Logs\DISM and the files created - I am attaching them here and if possible - you tell what and what are the errors.
You set DEFAULTLANGUAGE to BG, which is wrong the correct is bg-bg there are no errors in the logs, except the above are you sure you got all 4 errors as before? the slc.dll commands is just a workaround for a bug in 19044 first ISOs (SSU 19041.1220) it was fixed with SSU 19041.1371
I think I'm sure because from the script window I saw identical errors as my picture from the previous page and I didn't think I needed to take a new picture, but maybe I should have. As far as I understand - I will have to make the iso file again, but correctly write DEFAULTLANGUAGE to bg-bg. Later today - I will do this, with the correct language spelling, take a picture of the script window with the errors it will show and reattach the files located in C:\Windows\Logs\DISM. At least you know what to look for in them, I'm not familiar at least, but I got excited about adding a second language and it's actually very helpful.
I watched the script window the whole time and didn't see an error being written. The finished file now has a new name: 19044.1288.211006-0319.21H2_RELEASE_SVC_PROD1_CLIENT_X64FRE_BG_EN.iso. Now I plan to apply the said new iso file 19044.1288.211006-0319.21H2_RELEASE_SVC_PROD1_CLIENT_X64FRE_BG_EN.iso via Slimdown10 script By the way - I am attaching the files from C:\Windows\Logs\DISM so you can look at them and find out if everything is fine or if there is something wrong?! Thanks for this useful tool, it turned out to be possible even through my current Windows 7 x64 to add a second language to the Windows 10 iso.