Is there any way to solve this problem>

Yes: Find the incorrect code and provide a patch in Gerrit to make it correct code. :)

exception.message	       	Bad value for parameter $dbkey: invalid DB key 'Գոհար_Նալբանդյան_'
exception.trace
#0 /srv/mediawiki/php-1.34.0-wmf.8/includes/title/TitleValue.php(105): Wikimedia\Assert\Assert::parameter(boolean, string, string)
#1 /srv/mediawiki/php-1.34.0-wmf.8/includes/title/NamespaceInfo.php(162): TitleValue->__construct(integer, string)
#2 /srv/mediawiki/php-1.34.0-wmf.8/includes/Title.php(1523): NamespaceInfo->getTalkPage(Title)
#3 /srv/mediawiki/php-1.34.0-wmf.8/extensions/WikiLove/includes/WikiLoveHooks.php(166): Title->getTalkPage()
#4 /srv/mediawiki/php-1.34.0-wmf.8/extensions/WikiLove/includes/WikiLoveHooks.php(57): WikiLoveHooks::getUserTalkPage(Title, User)
#5 /srv/mediawiki/php-1.34.0-wmf.8/includes/Hooks.php(174): WikiLoveHooks::onBeforePageDisplay(OutputPage, SkinVector)
#6 /srv/mediawiki/php-1.34.0-wmf.8/includes/Hooks.php(234): Hooks::callHook(string, array, array, NULL, string)
#7 /srv/mediawiki/php-1.34.0-wmf.8/includes/OutputPage.php(2746): Hooks::runWithoutAbort(string, array)
#8 /srv/mediawiki/php-1.34.0-wmf.8/includes/MediaWiki.php(872): OutputPage->output(boolean)
#9 /srv/mediawiki/php-1.34.0-wmf.8/includes/MediaWiki.php(884): Closure$MediaWiki::main()
#10 /srv/mediawiki/php-1.34.0-wmf.8/includes/MediaWiki.php(515): MediaWiki->main()
#11 /srv/mediawiki/php-1.34.0-wmf.8/index.php(42): MediaWiki->run()
#12 /srv/mediawiki/w/index.php(3): include(string)
#13 {main}

I've reproduced this on en.wikipedia.org, and narrowed it down to a trailing space in the parent page title.

• Request URL: https://en.wikipedia.org/wiki/User:Example_/A
• Fatal exception: [XQE-QQpAMFcAACB6PpQAAAAS] 2019-06-12 18:06:58: Fatal exception of type "Wikimedia\Assert\ParameterAssertionException"

Note a space in before slash is entirely valid in MediaWiki. As demonstrated by this page on test2.wikipedia.org:

• https://test2.wikipedia.org/wiki/Sandbox2_/x

Note a space in before slash is entirely valid in MediaWiki.

It is, but it causes confusion when trying to remove a subpage suffix.

The problem lies with Title::getBaseText() / getSubpageText() / getRootText() which would cut away the suffix, but not trim any leading or trailing whitespace or underscores. Then getBaseTitle() / getRootTite() construct a new (invlid!) Title object from that, which then triggers an error when getTalkPage is called on it, because NamespaceInfo->getTalkPage(Title) tries to construct a TitleValue.

The expectation that has been broken is "it is possible to get the talk page of an invalid title".

My suggestion for fixing this would be to:

• introduce a trimTitle method in TitleParser
• use that to trim the return values of getBaseText and friends.
• maybe also use it in makeTitle; or let makeTitle fail when called on an invalid title - after all, it'S contract says "It's assumed that $ns and $title are safe", which is violated in this case.

A somewhat rougher approach would be to simply replace makeTitle with makeTitleSafe in getBaseTitle and getRootTitle.

Change 517014 had a related patch set uploaded (by Daniel Kinzler; owner: Daniel Kinzler):
[mediawiki/core@master] Title: ensure getBaseTitle and getRootTitle return valid Titles.

https://gerrit.wikimedia.org/r/517014

Change 517014 merged by jenkins-bot:
[mediawiki/core@master] Title: ensure getBaseTitle and getRootTitle return valid Titles

https://gerrit.wikimedia.org/r/517014

should be fixed now, waiting for this to go live to confirm

Change 521253 had a related patch set uploaded (by Urbanecm; owner: Daniel Kinzler):
[mediawiki/core@wmf/1.34.0-wmf.11] Title: ensure getBaseTitle and getRootTitle return valid Titles

https://gerrit.wikimedia.org/r/521253

Change 521253 merged by jenkins-bot:
[mediawiki/core@wmf/1.34.0-wmf.11] Title: ensure getBaseTitle and getRootTitle return valid Titles

https://gerrit.wikimedia.org/r/521253

Mentioned in SAL (#wikimedia-operations) [2019-07-08T11:44:33Z] <urbanecm@deploy1001> Synchronized php-1.34.0-wmf.11/includes/Title.php: SWAT: [[:gerrit:521253|Title: ensure getBaseTitle and getRootTitle return valid Titles]] (T225585) (duration: 00m 50s)

@daniel i've backported this into wmf.11 to speed up the fixing. Can you (or somebody else) verify it's indeed fixed now please?

In T225585#5312967, @Urbanecm wrote:

@daniel i've backported this into wmf.11 to speed up the fixing. Can you (or somebody else) verify it's indeed fixed now please?

The only thing I can do to verify is to click the link in the description and note that it indeed no longer triggers an error. I consider that fixed :)