>>> If the only problem is with non-readable property values then we could
>>> check for such values and not to write them to the desktop file.
>>>
>>> > Maybe solving Bug#24982 would help?

There is also bug#17090.

>>> This would help on reading the desktop, but maybe better not to save
>>> non-readable values in the first place.
>>
>> No.  If the problem is reading then that's where the solution
>> should be located - not writing.  It has happened quite a few
>> times that something unreadable by Emacs has later become
>> readable.
>
> You mean the print syntax changes to become readable?  But not that
> Emacs can later read some unreadable #<...> syntax, right?

Even when the print syntax becomes readable in later versions, we still
can't write such syntax because earlier Emacs versions should be able
to read the same desktop file.

> That could be useful in general, but solving this particular bug by
> avoiding writing unreadable objects as Juri suggests seems okay too (and
> much less work, hence more likely to actually happen instead of just
> sitting for years).

Do you think this patch covers all possible unreadable cases on writing?