k2pdfopt: optimizes PDFs for viewing on e-readers - Page 144

Doitsu · 10-16-2025, 12:37 PM

Quote:

Originally Posted by Juniper1997

Hi there! I'm trying to use the software on Mac OS but I can't get it to work. For context I'm on Mac OS Sequoia 15, I followed all the steps but it won't let me open it even in terminal because it says it can't verify if it has malware or not. I tried using the Calibre plugin and it didn't work either. Any help would be much appreciated!

Did you also follow the steps in the video on the Mac page?

Sseda · 10-17-2025, 04:39 PM

I have a problem with K2pdfopt. The issue is that after the PDF is converted, it doesn’t get saved and gives an error. I have tried everything, and I’ve entered the output folder path correctly, but it still doesn’t save. It didn’t have this problem at first.
I have uninstalled and reinstalled the application multiple times, but it opened again with the same settings. I couldn’t figure out what the problem is.

Doitsu · 10-18-2025, 04:22 AM

Quote:

Originally Posted by Sseda

I have a problem with K2pdfopt. The issue is that after the PDF is converted, it doesn’t get saved and gives an error.

I've just tested the latest Windows version in GUI mode and it's working fine.

What's the exact error message?
What's your operating system?
Does the output path contain Turkish characters or other non-ASCII characters? E.g. ş or ğ?

Sseda · 10-18-2025, 05:14 AM

Quote:

Originally Posted by Doitsu

I've just tested the latest Windows version in GUI mode and it's working fine.

What's the exact error message?
What's your operating system?
Does the output path contain Turkish characters or other non-ASCII characters? E.g. ş or ğ?

Hi Doitsu,

First of all, thank you very much for your reply.
1. The error message I get appears after the conversion is completed. When I click “Open file,” it says:
“Error: cannot open [book name]”
When I click “Open output folder,” the folder opens correctly, but the converted file isn’t there — it’s not saved.
2. I’m using Windows 10.
3. I tried renaming both the file and the book title to remove any special characters, but the problem still persists.

Any ideas on what might be causing this?

Thanks again for your help!

Doitsu · 10-18-2025, 05:37 AM

Quote:

Originally Posted by Sseda

Any ideas on what might be causing this?

Most likely, there's an issue with the pdf file that you're trying to convert. Since @willus hasn't visited MR in a while, you might want to contact him directly, via the the contact form on his website.

Sseda · 10-18-2025, 05:47 AM

Quote:

Originally Posted by Doitsu

Most likely, there's an issue with the pdf file that you're trying to convert. Since @willus hasn't visited MR in a while, you might want to contact him directly, via the the contact form on his website.

Yes, I thought of that too. I tried with different PDFs, but the result is the same — it doesn’t save.
Thank you for your attention.

willus · 10-18-2025, 12:59 PM

You're sure you have write permission to the folder and adequate space on your disk? Can you post a link to one of the PDFs? Or send it to me via private message? And/or can you post a screen shot of the conversion log--something like I've attached here?

Sseda · 10-19-2025, 06:26 AM

Quote:

Originally Posted by willus

You're sure you have write permission to the folder and adequate space on your disk? Can you post a link to one of the PDFs? Or send it to me via private message? And/or can you post a screen shot of the conversion log--something like I've attached here?

Hi,
I have checked that I have write permission to the folder and that there is enough space on my disk. The PDF file is not open in any program. I’ve attached a screenshot of the conversion log to better illustrate the issue.

willus · 10-19-2025, 11:00 AM

You'll probably have to take your attachment down as it is a copyrighted work, but I was able to download it and the conversion (using Kobo Clara HD) worked fine on my Windows 11 PC with Core i9-9900 CPU. It wrote a 653-page output file (see attached example--page 18).

Can you post a screenshot of the GUI showing the options you are using?

Sseda · 10-19-2025, 12:30 PM

Quote:

Originally Posted by willus

You'll probably have to take your post down as it is a copyrighted work, but I was able to download it and the conversion (using Kobo Clara HD) worked fine on my Windows 11 PC with Core i9-9900 CPU. It wrote a 653-page output file (see attached example--page 18).

Can you post a screenshot of the GUI showing the options you are using?

Thanks for your help! I found what happened — the output resolution was originally 1072x1317 and that worked fine. I changed it to 1072x1448, which caused the conversion to fail. Sorry for making you go through this for such a simple setting Your program is amazing, thanks for everything!

willus · 10-20-2025, 08:48 AM

I'm glad it worked, but that is strange. Changing the resolution from 1317 to 1448 pixels vertically should not cause the conversion to fail. It still worked fine on my Windows 11 PC. Can you try this:
1. Load your file.
2. Select "Restore Defaults" (lower pink button on GUI)
3. Select Kobo Clara HD
4. Change resolution to 1448 pixels
Does it still fail? Did you select any other non-default options?

Sseda · 10-21-2025, 06:24 AM

[QUOTE=willus;4544288]I'm glad it worked, but that is strange. Changing the resolution from 1317 to 1448 pixels vertically should not cause the conversion to fail. It still worked fine on my Windows 11 PC. Can you try this:
1. Load your file.
2. Select "Restore Defaults" (lower pink button on GUI)
3. Select Kobo Clara HD
4. Change resolution to 1448 pixels
Does it still fail? Did you select any other non-default options?[/QUOTE

I wanted to share an issue I encountered during PDF conversion.

When the device Kobo Clara HD is selected and Conversion Mode “Fit Width” is used, Native PDF output is automatically enabled. If the Color output option is also selected, the program produces errors or fails to save the PDF correctly.
• When Negative/native output is disabled and Color output remains enabled, the PDF converts successfully.
• The issue is caused by Color output and Native PDF output being enabled at the same time, not by changing the resolution (px).
• This is due to the setting combination, not the PDF itself.

willus · 10-21-2025, 08:46 AM

I was able to reproduce your issue. I'll look into it. Thank you for bringing it to my attention. A quick check I did shows that the conversion is successful for a smaller number of pages. I converted pages 1-50 successfully, but not the entire book.

Sseda · 10-21-2025, 09:13 AM

Quote:

Originally Posted by willus

I was able to reproduce your issue. I'll look into it. Thank you for bringing it to my attention. A quick check I did shows that the conversion is successful for a smaller number of pages. I converted pages 1-50 successfully, but not the entire book.

Thanks a lot! I’m really glad we got the issue sorted out. The program is amazing and very useful.

willus · Yesterday, 10:54 AM

The last page of your document causes the problem. If you convert pp. 1-323, it is fine. The last page is completely blank. I'll note it as a bug.

10-17-2025, 04:39 PM	#2147
Sseda Junior Member Posts: 8 Karma: 55654 Join Date: Oct 2025 Device: Kobo clara Color	Merhaba I have a problem with K2pdfopt. The issue is that after the PDF is converted, it doesn’t get saved and gives an error. I have tried everything, and I’ve entered the output folder path correctly, but it still doesn’t save. It didn’t have this problem at first. I have uninstalled and reinstalled the application multiple times, but it opened again with the same settings. I couldn’t figure out what the problem is. Last edited by Sseda; 10-17-2025 at 04:43 PM.

10-18-2025, 12:59 PM	#2152
willus Fuzzball, the purple cat Posts: 1,312 Karma: 11087488 Join Date: Jun 2011 Location: California Device: iPad	You're sure you have write permission to the folder and adequate space on your disk? Can you post a link to one of the PDFs? Or send it to me via private message? And/or can you post a screen shot of the conversion log--something like I've attached here? Attached Thumbnails Last edited by willus; 10-18-2025 at 01:05 PM.

10-19-2025, 11:00 AM	#2154
willus Fuzzball, the purple cat Posts: 1,312 Karma: 11087488 Join Date: Jun 2011 Location: California Device: iPad	You'll probably have to take your attachment down as it is a copyrighted work, but I was able to download it and the conversion (using Kobo Clara HD) worked fine on my Windows 11 PC with Core i9-9900 CPU. It wrote a 653-page output file (see attached example--page 18). Can you post a screenshot of the GUI showing the options you are using? Attached Thumbnails Last edited by willus; 10-21-2025 at 08:46 AM.

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10-20-2025, 08:48 AM	#2156
willus Fuzzball, the purple cat Posts: 1,312 Karma: 11087488 Join Date: Jun 2011 Location: California Device: iPad	I'm glad it worked, but that is strange. Changing the resolution from 1317 to 1448 pixels vertically should not cause the conversion to fail. It still worked fine on my Windows 11 PC. Can you try this: 1. Load your file. 2. Select "Restore Defaults" (lower pink button on GUI) 3. Select Kobo Clara HD 4. Change resolution to 1448 pixels Does it still fail? Did you select any other non-default options?

10-21-2025, 06:24 AM	#2157
Sseda Junior Member Posts: 8 Karma: 55654 Join Date: Oct 2025 Device: Kobo clara Color	[QUOTE=willus;4544288]I'm glad it worked, but that is strange. Changing the resolution from 1317 to 1448 pixels vertically should not cause the conversion to fail. It still worked fine on my Windows 11 PC. Can you try this: 1. Load your file. 2. Select "Restore Defaults" (lower pink button on GUI) 3. Select Kobo Clara HD 4. Change resolution to 1448 pixels Does it still fail? Did you select any other non-default options?[/QUOTE I wanted to share an issue I encountered during PDF conversion. When the device Kobo Clara HD is selected and Conversion Mode “Fit Width” is used, Native PDF output is automatically enabled. If the Color output option is also selected, the program produces errors or fails to save the PDF correctly. • When Negative/native output is disabled and Color output remains enabled, the PDF converts successfully. • The issue is caused by Color output and Native PDF output being enabled at the same time, not by changing the resolution (px). • This is due to the setting combination, not the PDF itself.

10-21-2025, 08:46 AM	#2158
willus Fuzzball, the purple cat Posts: 1,312 Karma: 11087488 Join Date: Jun 2011 Location: California Device: iPad	I was able to reproduce your issue. I'll look into it. Thank you for bringing it to my attention. A quick check I did shows that the conversion is successful for a smaller number of pages. I converted pages 1-50 successfully, but not the entire book.

Yesterday, 10:54 AM	#2160
willus Fuzzball, the purple cat Posts: 1,312 Karma: 11087488 Join Date: Jun 2011 Location: California Device: iPad	The last page of your document causes the problem. If you convert pp. 1-323, it is fine. The last page is completely blank. I'll note it as a bug.