Comment # 2 on bug 1067656 from Tristan Miller

I am experiencing the same problem, which occurs both when saving attachments
and adding them to messages.

When adding or saving an attachment, the file selector dialog appears, but
after selecting a location, the attachment usually doesn't get attached/saved.
No error dialog is displayed, though an error message does appear in the Error
Console. If I repeat the process, it usually (but not always) works the second
time around.

Sample steps to reproduce: Right-click on a message attachment. Select "Save
As���". File dialog pops up. Navigate to a directory in which to save the file
and press "Save", or simply type a full path in the "Name" field and press
enter. The file dialog disappears, but the file doesn't get saved to the
directory. The following gets logged to the Error Console:

> 14:52:53.968 NS_ERROR_MALFORMED_URI: Component returned failure code: 0x804b000a (NS_ERROR_MALFORMED_URI) [nsIMessenger.saveAttachment] 1 msgHdrViewOverlay.js:1835
>	AttachmentInfo_save chrome://messenger/content/msgHdrViewOverlay.js:1835:5
>	HandleMultipleAttachments/actionFunction chrome://messenger/content/msgHdrViewOverlay.js:2704:50
>	HandleMultipleAttachments chrome://messenger/content/msgHdrViewOverlay.js:2708:11
>	oncommand chrome://messenger/content/messenger.xul:1:1

I am using MozillaThunderbird-52.4.0-1.1.x86_64 from the Mozilla repository on
openSUSE 42.3.  So far I haven't been able to reproduce it in safe mode, though
it does happen in normal mode with all add-ons disabled.  I haven't been able
to reproduce it with the official Mozilla binaries.

I believe the problem may be linked to kmozillahelper (which makes Thunderbird
use the KDE file selection dialogs rather than the GTK+ ones).  When I
uninstall kmozillahelper, I am no longer able to reproduce the problem.  This
probably also explains why the problem is not reproducible with the official
Thunderbird build.