Double check the path to the folder it's supposed to save images to.

I had this error a couple of times when my usb stick mounted differently for some reason.

Thank you, maxthebuilder. I have checked the path and it seems to be OK. I have even tried both local and remote paths. But again no success.

I'm sorry I haven't replied earlier, this week was intense on my job.

Spent this afternoon trying to make this work but again no success. Tried many different configurations combination.
It's sad that I got so far but got stuck here, I'm almost giving up.

Did you check the rest of troubleshooting tips ?

Also, run this command, does it work? Either way, post the log:

Once again, thank you knro.

I took the time to carefully read the entire page you sent me and all this thing regarding the "force bulb" for longer exposures and manual for exposures less than a second caught my attention. So I've tried to capture a 10" long picture and got success. The camera was on "M" and "force bulb" was set to be active on Ekos. This whole time I was trying shorter exposures.

That's a good thing!

But then I tried to take a fast exposure like 1/100". The camera was on "M" and "force bulb" as set to be off on Ekos. I've set the exposure time to be 0.01, which is a predefined shutter speed on this particular model (1/100). But just changing this (force bulb to off and exposure time to 0.01) made it fail again.

That's the complete log of actions, with the successful 10" exposure, and the failed 1/100" exposure after (on top):

So as you can see the 10" (actually for some reason that I don't know it's 10.3") works right away with BULB mode enabled. Then I disabled bulb (as I'm going to perform a short exposure) and proceed to test the 0.01" exposure, which fails triggering a retry from Ekos.

I then tried the 0.01" exposure with "force bulb" enabled, just for curiosity. But it also failed:

So in other words, only long exposures with "force bulb" enabled are working for me at this moment. Any idea?

Now regarding this gphoto2 command, I logged on the Pi's SSH and with the INDI server stooped I executed it, took around 2 minutes to finish:

The complete log is here: gist.github.com/fschuindt/d2a5f3b0fab08d873716d21dd4a5c2ab

It's a huge file, more than 14k lines.

Side note I had to install gphoto2 in order to run this command, it was't installed before. But I think that makes sense since I believe I'm using a DSLR-specific driver instead of the gphoto driver, right?

I think that's it. Any tips/clues/ideas?
Thank you all for the support!

I was once again playing with Ekos and noticed the capture is only working if the exposure time is longer than 1.8". Anything shorter than that will yield the same error I described on the original post.

Even with "force bulb" disabled, it seems as if it's always trying to do bulb. I'm not sure.

Another thing I noticed, is that if I set a 3" long exposure on Ekos, it works, but the .CR2 file metadata will display the exposure time as 1.0", not 3.0".

As stated before, I'm using a Mirror Lock. But I noticed something strange: When I set a 3" long exposure, I hear 4 clicks. The first and the last are loud. But the two of the middle are quiet.
So I think the first and the last are the mirror moving up and down, and the other two are the opening and closing of the sensor to perform the exposure itself. But I see that the exposure countdown starts on the first click, not on the second one. So I think that kinda explains why I have a 1.0" exposure metadata when I ask for a 3.0" one. 2" were spent on the mirror lock delay. (2" is my mirror lock delay)

Not good.

So I tried disabling the mirror lock, both on Ekos and both on the camera settings. On Ekos I haven't found a "disable mirror lock" specific config., so I've set the Mirror Lock to 0". But after doing this I'm no longer able to take any pictures, not even the long exposures. The camera remains completely silent when the Ekos log displays attempts to capture the image. In other words I can only take pictures when I have Mirror Lock enabled.

But even so, not short exposures as I said. And even the longer ones seems a little bit messed. Like 3" exposing only 1" on reality.

Also, I don't think that calculating Mirror Lock delay + exposure time works. Using a 2" mirror lock and commanding Ekos to expose 3" and later 2.8" will both yield a .CR2 file with a 1.0" exposure on the metadata. (I was expecting to get one as a 0.8" exposure)

All of this made me wonder if there's someone reliably using INDI+Ekos to work with DSLR cameras. Because I don't feel it's production ready at all to be honest. (I'm eager to help)

Is there anyway to take short exposures (like 0.8") on Canon DSLRs?

Thank you!

I have 600D and just used it to take all kind of different exposures.. this is my development camera so I know that ALL the features work quite well. Maybe this is somehow related to Manjero? Not sure why, but if you use it with another distribution (raspbian or ubuntu).. same issue? Mabye the libgphoto2 is not the same.

I'm going to try a different OS this weekend. But in the meantime...

Are you able to use this camera without Mirror Lock?
Disabling Mirror Lock is just a matter or setting the Mirror Lock time to 0 on Ekos and set it to be "off" on the camera menu?

Apart from disabling "force bulb" and picking a predefined exposure time, what else do you ensure is set in order to take short exposures?

Thank you.

Yes I tested it with and without mirror lock. Set it to 0 to disable it as you already figured it out. With 600D, I actually don't do any changes to take short or long exposures, it works equally well on both. I take take from 1/8000s to 300s without touching any settings.

I see, it's indeed boiling down to a OS suspicion. This weekend I'm going to "dd" the current SD card of the Pi to backup, and then try it with Ubuntu. Do you think that the client OS will matter? Because my laptop is also running Manjaro.

Thank you.

I got it! Turns out this whole time I was using the "Canon DSLR" CCD driver, I changed it to "GPhoto CCD" and everything is working just fine. All kinds of exposures.

I don't know why, but it wasn't clear to me I should't use a Canon DSLR driver if I have a Canon DSLR. lol

Anyway, I'm sorry for all the "back and forward" I created and also for my drastic thoughts.
I'm really happy I have this working now.

Thank you all that put efforts into thinking about this.
Thank you knro for all the attention.

Canon driver uses also libgphoto2 but it is slightly different in the way it queries and connects to the camera in order to provide a fuller support. But they're 99% identical otherwise.