Importing book names from goodreads.com into Google Sheets with ImportXML gives "Import Internal Error" sometimes - xpath

Question

I have a formula that fetches names of books from goodreads.com:
=IMPORTXML("https://www.goodreads.com/book/show/" & gr_id; "//*[#id='bookTitle']")
where gr_id is a column containing ids of the books. For example when gr_id=23848607, it fetches from URL https://www.goodreads.com/book/show/23848607 and the result is "Warheart".
The formula worked fine some time ago. I did not change anything and now I noticed it stopped working for some of the books (still working for others). Instead of the name of the book now it gives N/A with "Import Internal Error" hint. The ids that do not work are:
48332548
35906922
How to make it work for all books?
There were many questions posted about "Import Internal Error" problems. I tried some solutions including copying the formula to a fresh sheet, but it did not work.
Update: I tried the following different XPath formulas instead of "//*[#id='bookTitle']".
"//h1[#id='bookTitle']"
"//h1"
Those different XPath formulas worked the same as the original XPath formula. They worked correctly for the same ids that the original one did and produced N/As for the same ids that the original one did.
Update: I just re-checked and all my formulas worked correctly for all gr_ids (I had not changed anything since the time when they did not work.) May be someone knows how to prevent them from stopping working in the future.
Update: I re-checked once again. Of all gr_ids only this one was showing N\A now: 35906922. I created an example spreadsheet, because my working spreadsheet contains too many unrelated details, but the problem did not appear in the example spreadsheet. I went back to my working spreadsheet and reloaded it - and the problem disappeared in my working spreadsheet too. Then I added more test data in the example spreadsheet and the following new example gr_ids showed N\A:
48213012
48213092
I tried to make a copy of the example spreadsheet to see if it fixes the problem. The behavior in the copy example spreadsheet was identical to the original example spreadsheet - the problem only with two gr_ids specified above.

Answer 1

if you run full IMPORTXML on those two IDs you can see it won't return anything at all:
=IMPORTXML("https://www.goodreads.com/book/show/48213012-fathers-and-sons", "//*")
which means that Google Sheets can't reach the XML content for some reason (could be something similar to https://stackoverflow.com/a/24891676/5632629)
therefore we can try to read the source code directly with IMPORTDATA where we can find around 70 elements with the same information so we pick one, isolate it and remove HTML tags. then we just wrap the prior formula in IFERROR and force the formula to take a 2nd look if it fails first time. the result is like this:
=IFERROR(IMPORTXML("https://www.goodreads.com/book/show/"&A:A, "//*[#id='bookTitle']"),
REGEXEXTRACT(QUERY(ARRAY_CONSTRAIN(
IMPORTDATA("https://www.goodreads.com/book/show/"&A:A), 100, 1),
"select Col1 where Col1 contains '</title>'"), ">(.*) by"))

Answer 2

IMPORTXML() seems to be unreliable. I decided not to use it, because I did not find an acceptable solution to my problem. Instead of using IMPORTXML() I exported my books from goodreads.com to csv file (there is such a feature of goodreads.com) and then imported the csv file into my spreadsheet. This is not be an perfect solution, because I need to re-import every time I need to update the books, but at least it works.