[davidfor]

Originally Posted by Blas

I only have books, no pdfs or comics. All of them were imported by the Kobo Touch extension on Calibre. They are not that big, they have the average size you know. I really think that I have a lot of books with issues which I don't really know how to fix.

My mistake. I misread your post about space. I read it as 28.3GB used, not free. That's a lot more like it.

What do you mean about "generate and send the covers"? By updating the metadata?

The driver, in your case the KoboTouchExtended driver, has a lot of options. Some of these will mean sending the cover images with the books rather than letting the device generate them. Once you turn the option on, it is all automatic.

To turn the option on, while the device is connected, right-click on the device button and select "Configure this device". The configuration dialog will open. Select the "Collections, covers & uploads" tab. In the middle, select the "Upload covers" and then the other options you like the look of. Save the changes and restart calibre. After this, when you send a book to a Kobo device, the cover will be generated by the driver and put onto the device. I think this will probably solve the problem you are seeing.

My sdCard is class 10. So I think it's not the problem. I must be the books cuz when I remove a certain amount till October, it starts to load the covers normally.

There has been some discussion about the best card to use in the Kobo forums. I think it comes down to quality of the card more than the class.

[EDIT] I forgot to ask, what tool can I use to automatically check and fix my books? I don't have any knowledge about fixing it tbh.

I don't have a good answer to that. I spend far to much time editing my books to be how I want. I use the calibre editor, but I could also use Sigil. Both are good epub editors and both have functions to check for errors and help you fix them. But, in most cases this is overkill.

A simpler method is to do an epub-to-epub conversion. This will nearly always produce a book the Kobo devices will handle with no problems. Some people will say not to do this as it messes with the internals of books in ways they don't like. But, unless you start editing the books, that doesn't really matter. The conversion can change the look of a book, and there are options to change some things. But, you can also use this to make the books how you like. For example, if you want a gap between the paragraphs instead of an indent at the start, you can do this on the "Look & feel" page of the conversion.

My suggestion is to only do something if there seems to be a problem. If the book isn't imported, then you can either do the conversion or open it in the editor and run the check function (press the button that looks like a bug). This give some help on fixing any problems or and there is an option to automatically fix some.