How to fix an error that shows "file not found" or "input/output error" when saving?

First the nitty gritty:
OS: Win 10 Pro
LibreOffice: 5.3.7.2

As of three days ago my LibreOffice stopped saving files in both Writer and Calc at least. When saving an existing file with modifications I get an error stating:

Error saving the document XXXX: General input/output error
while accessing
C:\Users\Inky\Documents\XXX

If I try to save a new file I get an error stating:

Error saving the document Untitled 1:
General input/output error while
accessing
C:\Users\Inky\Documents\XXXX

After trying to find anyone else with this problem and failing, I uninstalled and reinstalled LibreOffice. Now I get the document properties window before getting the second error message while trying to save a new file.

As far as I know I have no changes to my system, though I do have a toddler and she likes to push buttons.

Any thoughts?

Do you happen to have Windows Defender running?

Try to save something else (other than using LibreOffice) into C:\Users\Inky\Documents. For example, save a copy of this webpage into that directory. If it doesn’t work, the problem is not limited to LibreOffice.

You said it yourself: ’ …the nitty gritty: OS: Win 10 Pro…’

Sorry, could not help myself.

@robleyd Yes I do. Is that a possible source of the problem?

@Context15 Saving a copy of this page to that folder worked just fine. So it’s something else. Any idea?

If Windows Defender is running, you will need to add the LO executable - soffice.bin (tC:\Program Files\LibreOffice5\program\soffice.bin on my Win 7 32bit)) - as an allowed application; see How to Change Windows Defender Controlled Folder Access Settings in Windows 10

If this answer helped you, please accept it by clicking the check mark :heavy_check_mark: to the left and, karma permitting, upvote it. If this resolves your problem, close the question, that will help other people with the same question.

[Edit 2018-01-20] For reference, this is a snap of (some of) the LO 5.3.7 program files in my Win 7 Ultimate virtual machine.

Well that did point me in the correct direction but the new issue is I cannot find the core LibreOffice apps, only their shortcuts. This means I cannot use those apps as declared exceptions since they simply do not work. Even with reboots. So do you know where the core program exist because all I can find is swriter and the like.

Meanwhile I have implemented a workaround of a unprotected folder.

Is soffice.bin not in the path I mentioned above?

No I have C:\Program Files\LibreOffice5\program\soffice.exe. But I still have no save functionality with that in place. Very confused here.

“With that in place” I take to mean added as an allowed application? To confirm that Controlled Folder Access is in fact the problem you could try turning it off completely - see the link in my answer - and see if the problem is resolved that way. Beyond that I don’t have any further advice, not having W10 available to experiment with

For reference: when adding to controlled folder access exceptions list, the File Open dialog only has *.com and *.exe in its file type list. This filters out any files with other extensions, including soffice.bin.

One might start typing “soffice” into File Name box (when in LibreOffice\program folder), and pick soffice.bin from the drop-down list of matching files; or one can put * there, press enter, and see all files (including soffice.bin).

I had to type soffice.bin into the filename box beside the Open button, as I could only see soffice.exe - I guess the .bin files are hidden in the open/select file screen.