I got this strange error.

On my 'dev' it works with:

// Enable Translations
i18n::enable();
i18n::set_locale('nl_NL');
i18n::set_default_lang('nl_NL');

I get an error when I change set_default_lang() to 'nl'

On my 'live' it works with:

// Enable Translations
i18n::enable();
i18n::set_locale('nl_NL');
i18n::set_default_lang('nl');

For example on 'live' I get this error when I change set_default_lang() to nl_NL:

[User Error] Couldn't run query: SELECT `SiteTree_versions`.RecordID FROM `SiteTree_lang_versions` INNER JOIN `SiteTree_versions` ON `SiteTree_lang_versions`.OriginalLangID = `SiteTree_versions`.ID LEFT JOIN `Page_versions` ON `Page_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `GhostPage_versions` ON `GhostPage_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `BlogEntry_versions` ON `BlogEntry_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `BlogHolder_versions` ON `BlogHolder_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `CheckoutPage_versions` ON `CheckoutPage_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `Product_versions` ON `Product_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `ProductGroup_versions` ON `ProductGroup_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `ArticlePage_versions` ON `ArticlePage_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `SchouwenPage_versions` ON `SchouwenPage_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `SleperPage_versions` ON `SleperPage_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `WachtschepenPage_versions` ON `WachtschepenPage_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `ErrorPage_versions` ON `ErrorPage_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `RedirectorPage_versions` ON `RedirectorPage_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `VirtualPage_versions` ON `VirtualPage_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `UserDefinedForm_versions` ON `UserDefinedForm_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `SubscribeForm_versions` ON `SubscribeForm_versions`.ID = `SiteTree_lang_versions`.OriginalLangID WHERE (`SiteTree_lang_versions`.Lang = 'nl') AND (`SiteTree_versions`.`WasPublished` = 1 AND `URLSegment` = 'home') ORDER BY `LastEdited` DESC, `SiteTree_versions`.`WasPublished` LIMIT 1 Column 'URLSegment' in where clause is ambiguous
GET /

Line 400 in /home/knr11075/domains/waterscouting.com/public_html/frontpage/sapphire/core/model/MySQLDatabase.php

Source

391 	}
392 	
393 	function databaseError($msg, $errorLevel = E_USER_ERROR) {
394 		// try to extract and format query
395 		if(preg_match('/Couldn\'t run query: ([^\|]*)\|\s*(.*)/', $msg, $matches)) {
396 			$formatter = new SQLFormatter();
397 			$msg = "Couldn't run query: \n" . $formatter->formatPlain($matches[1]) . "\n\n" . $matches[2];
398 		}
399 		
400 		user_error($msg, $errorLevel);
401 	}
402 }
403 
404 /**
405  * A result-set from a MySQL database.
406  * @package sapphire
Trace

Couldn't run query: SELECT `SiteTree_versions`.RecordID FROM `SiteTree_lang_versions` INNER JOIN `SiteTree_versions` ON `SiteTree_lang_versions`.OriginalLangID = `SiteTree_versions`.ID LEFT JOIN `Page_versions` ON `Page_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `GhostPage_versions` ON `GhostPage_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `BlogEntry_versions` ON `BlogEntry_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `BlogHolder_versions` ON `BlogHolder_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `CheckoutPage_versions` ON `CheckoutPage_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `Product_versions` ON `Product_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `ProductGroup_versions` ON `ProductGroup_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `ArticlePage_versions` ON `ArticlePage_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `SchouwenPage_versions` ON `SchouwenPage_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `SleperPage_versions` ON `SleperPage_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `WachtschepenPage_versions` ON `WachtschepenPage_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `ErrorPage_versions` ON `ErrorPage_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `RedirectorPage_versions` ON `RedirectorPage_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `VirtualPage_versions` ON `VirtualPage_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `UserDefinedForm_versions` ON `UserDefinedForm_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `SubscribeForm_versions` ON `SubscribeForm_versions`.ID = `SiteTree_lang_versions`.OriginalLangID WHERE (`SiteTree_lang_versions`.Lang = 'nl') AND (`SiteTree_versions`.`WasPublished` = 1 AND `URLSegment` = 'home') ORDER BY `LastEdited` DESC, `SiteTree_versions`.`WasPublished` LIMIT 1 Column 'URLSegment' in where clause is ambiguous 
Line 400 of MySQLDatabase.php
MySQLDatabase->databaseError(Couldn't run query: SELECT `SiteTree_versions`.RecordID FROM `SiteTree_lang_versions` INNER JOIN `SiteTree_versions` ON `SiteTree_lang_versions`.OriginalLangID = `SiteTree_versions`.ID LEFT JOIN `Page_versions` ON `Page_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `GhostPage_versions` ON `GhostPage_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `BlogEntry_versions` ON `BlogEntry_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `BlogHolder_versions` ON `BlogHolder_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `CheckoutPage_versions` ON `CheckoutPage_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `Product_versions` ON `Product_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `ProductGroup_versions` ON `ProductGroup_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `ArticlePage_versions` ON `ArticlePage_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `SchouwenPage_versions` ON `SchouwenPage_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `SleperPage_versions` ON `SleperPage_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `WachtschepenPage_versions` ON `WachtschepenPage_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `ErrorPage_versions` ON `ErrorPage_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `RedirectorPage_versions` ON `RedirectorPage_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `VirtualPage_versions` ON `VirtualPage_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `UserDefinedForm_versions` ON `UserDefinedForm_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `SubscribeForm_versions` ON `SubscribeForm_versions`.ID = `SiteTree_lang_versions`.OriginalLangID WHERE (`SiteTree_lang_versions`.Lang = 'nl') AND (`SiteTree_versions`.`WasPublished` = 1 AND `URLSegment` = 'home') ORDER BY `LastEdited` DESC, `SiteTree_versions`.`WasPublished` LIMIT 1 | Column 'URLSegment' in where clause is ambiguous,256) 
Line 102 of MySQLDatabase.php
MySQLDatabase->query(SELECT `SiteTree_versions`.RecordID FROM `SiteTree_lang_versions` INNER JOIN `SiteTree_versions` ON `SiteTree_lang_versions`.OriginalLangID = `SiteTree_versions`.ID LEFT JOIN `Page_versions` ON `Page_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `GhostPage_versions` ON `GhostPage_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `BlogEntry_versions` ON `BlogEntry_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `BlogHolder_versions` ON `BlogHolder_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `CheckoutPage_versions` ON `CheckoutPage_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `Product_versions` ON `Product_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `ProductGroup_versions` ON `ProductGroup_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `ArticlePage_versions` ON `ArticlePage_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `SchouwenPage_versions` ON `SchouwenPage_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `SleperPage_versions` ON `SleperPage_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `WachtschepenPage_versions` ON `WachtschepenPage_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `ErrorPage_versions` ON `ErrorPage_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `RedirectorPage_versions` ON `RedirectorPage_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `VirtualPage_versions` ON `VirtualPage_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `UserDefinedForm_versions` ON `UserDefinedForm_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `SubscribeForm_versions` ON `SubscribeForm_versions`.ID = `SiteTree_lang_versions`.OriginalLangID WHERE (`SiteTree_lang_versions`.Lang = 'nl') AND (`SiteTree_versions`.`WasPublished` = 1 AND `URLSegment` = 'home') ORDER BY `LastEdited` DESC, `SiteTree_versions`.`WasPublished` LIMIT 1,256) 
Line 104 of DB.php
DB::query(SELECT `SiteTree_versions`.RecordID FROM `SiteTree_lang_versions` INNER JOIN `SiteTree_versions` ON `SiteTree_lang_versions`.OriginalLangID = `SiteTree_versions`.ID LEFT JOIN `Page_versions` ON `Page_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `GhostPage_versions` ON `GhostPage_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `BlogEntry_versions` ON `BlogEntry_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `BlogHolder_versions` ON `BlogHolder_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `CheckoutPage_versions` ON `CheckoutPage_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `Product_versions` ON `Product_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `ProductGroup_versions` ON `ProductGroup_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `ArticlePage_versions` ON `ArticlePage_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `SchouwenPage_versions` ON `SchouwenPage_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `SleperPage_versions` ON `SleperPage_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `WachtschepenPage_versions` ON `WachtschepenPage_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `ErrorPage_versions` ON `ErrorPage_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `RedirectorPage_versions` ON `RedirectorPage_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `VirtualPage_versions` ON `VirtualPage_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `UserDefinedForm_versions` ON `UserDefinedForm_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `SubscribeForm_versions` ON `SubscribeForm_versions`.ID = `SiteTree_lang_versions`.OriginalLangID WHERE (`SiteTree_lang_versions`.Lang = 'nl') AND (`SiteTree_versions`.`WasPublished` = 1 AND `URLSegment` = 'home') ORDER BY `LastEdited` DESC, `SiteTree_versions`.`WasPublished` LIMIT 1) 
Line 426 of SQLQuery.php
SQLQuery->execute() 
Line 106 of ModelAsController.php
ModelAsController->findOldPage(home) 
Line 47 of ModelAsController.php
ModelAsController->getNestedController() 
Line 25 of ModelAsController.php
ModelAsController->handleRequest(HTTPRequest) 
Line 34 of RootURLController.php
RootURLController->handleRequest(HTTPRequest) 
Line 277 of Director.php
Director::handleRequest(HTTPRequest,Session) 
Line 121 of Director.php
Director::direct() 
Line 115 of main.php

I got these error too, I'll investigate more, but I think the problem is change default parameters with site already created.
Ex.:
SStripe installed and you put some entries in site after then change languages value, SStripe create some wrong MySQL query, SStripe don't work well with this yet I think.
Maybe the solution for this problem will be resolved soon, the SStripe team is great.

Try to test in a clean database install, make new database in your MySQL then change _config.php to point to this new database then run http://mysite/db/build to create a new fresh db.

P.S. please your setup language configuration before db/build.
Hope this help

Peace

Sorry but it will not work, I'll put my debug out for someone help to debug.
I'm using pt-BR.

my _config.php
i18n::enable();
i18n::set_default_lang('pt-BR');
i18n::set_locale('pt_BR');

When I comment i18n::enable or use i18n:disable the problem goes away, but just i18n::set_locale does not work alone.
My Output debug:

[User Error] Couldn't run query: SELECT `SiteTree_versions`.RecordID FROM `SiteTree_lang_versions` INNER JOIN `SiteTree_versions` ON `SiteTree_lang_versions`.OriginalLangID = `SiteTree_versions`.ID LEFT JOIN `GhostPage_versions` ON `GhostPage_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `BlogEntry_versions` ON `BlogEntry_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `BlogHolder_versions` ON `BlogHolder_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `Forum_versions` ON `Forum_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `ForumHolder_versions` ON `ForumHolder_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `GameFlash_versions` ON `GameFlash_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `GoogleCustomSearch_versions` ON `GoogleCustomSearch_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `ErrorPage_versions` ON `ErrorPage_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `RedirectorPage_versions` ON `RedirectorPage_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `VirtualPage_versions` ON `VirtualPage_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `UserDefinedForm_versions` ON `UserDefinedForm_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `SubscribeForm_versions` ON `SubscribeForm_versions`.ID = `SiteTree_lang_versions`.OriginalLangID WHERE (`SiteTree_versions`.SubsiteID IN (0)) AND (`SiteTree_lang_versions`.Lang = 'pt') AND (`SiteTree_versions`.`WasPublished` = 1 AND `URLSegment` = 'home') ORDER BY `LastEdited` DESC, `SiteTree_versions`.`WasPublished` LIMIT 1 Column 'URLSegment' in where clause is ambiguous
GET /

Line 400 in /home/shingo/Documents/Repositories/someunet/sapphire/core/model/MySQLDatabase.php
Source

391 }
392
393 function databaseError($msg, $errorLevel = E_USER_ERROR) {
394 // try to extract and format query
395 if(preg_match('/Couldn\'t run query: ([^\|]*)\|\s*(.*)/', $msg, $matches)) {
396 $formatter = new SQLFormatter();
397 $msg = "Couldn't run query: \n" . $formatter->formatPlain($matches[1]) . "\n\n" . $matches[2];
398 }
399
400 user_error($msg, $errorLevel);
401 }
402 }
403
404 /**
405 * A result-set from a MySQL database.
406 * @package sapphire

Trace

* Couldn't run query: SELECT `SiteTree_versions`.RecordID FROM `SiteTree_lang_versions` INNER JOIN `SiteTree_versions` ON `SiteTree_lang_versions`.OriginalLangID = `SiteTree_versions`.ID LEFT JOIN `GhostPage_versions` ON `GhostPage_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `BlogEntry_versions` ON `BlogEntry_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `BlogHolder_versions` ON `BlogHolder_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `Forum_versions` ON `Forum_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `ForumHolder_versions` ON `ForumHolder_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `GameFlash_versions` ON `GameFlash_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `GoogleCustomSearch_versions` ON `GoogleCustomSearch_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `ErrorPage_versions` ON `ErrorPage_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `RedirectorPage_versions` ON `RedirectorPage_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `VirtualPage_versions` ON `VirtualPage_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `UserDefinedForm_versions` ON `UserDefinedForm_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `SubscribeForm_versions` ON `SubscribeForm_versions`.ID = `SiteTree_lang_versions`.OriginalLangID WHERE (`SiteTree_versions`.SubsiteID IN (0)) AND (`SiteTree_lang_versions`.Lang = 'pt') AND (`SiteTree_versions`.`WasPublished` = 1 AND `URLSegment` = 'home') ORDER BY `LastEdited` DESC, `SiteTree_versions`.`WasPublished` LIMIT 1 Column 'URLSegment' in where clause is ambiguous
Line 400 of MySQLDatabase.php
* MySQLDatabase->databaseError(Couldn't run query: SELECT `SiteTree_versions`.RecordID FROM `SiteTree_lang_versions` INNER JOIN `SiteTree_versions` ON `SiteTree_lang_versions`.OriginalLangID = `SiteTree_versions`.ID LEFT JOIN `GhostPage_versions` ON `GhostPage_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `BlogEntry_versions` ON `BlogEntry_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `BlogHolder_versions` ON `BlogHolder_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `Forum_versions` ON `Forum_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `ForumHolder_versions` ON `ForumHolder_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `GameFlash_versions` ON `GameFlash_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `GoogleCustomSearch_versions` ON `GoogleCustomSearch_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `ErrorPage_versions` ON `ErrorPage_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `RedirectorPage_versions` ON `RedirectorPage_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `VirtualPage_versions` ON `VirtualPage_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `UserDefinedForm_versions` ON `UserDefinedForm_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `SubscribeForm_versions` ON `SubscribeForm_versions`.ID = `SiteTree_lang_versions`.OriginalLangID WHERE (`SiteTree_versions`.SubsiteID IN (0)) AND (`SiteTree_lang_versions`.Lang = 'pt') AND (`SiteTree_versions`.`WasPublished` = 1 AND `URLSegment` = 'home') ORDER BY `LastEdited` DESC, `SiteTree_versions`.`WasPublished` LIMIT 1 | Column 'URLSegment' in where clause is ambiguous,256)
Line 102 of MySQLDatabase.php
* MySQLDatabase->query(SELECT `SiteTree_versions`.RecordID FROM `SiteTree_lang_versions` INNER JOIN `SiteTree_versions` ON `SiteTree_lang_versions`.OriginalLangID = `SiteTree_versions`.ID LEFT JOIN `GhostPage_versions` ON `GhostPage_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `BlogEntry_versions` ON `BlogEntry_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `BlogHolder_versions` ON `BlogHolder_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `Forum_versions` ON `Forum_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `ForumHolder_versions` ON `ForumHolder_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `GameFlash_versions` ON `GameFlash_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `GoogleCustomSearch_versions` ON `GoogleCustomSearch_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `ErrorPage_versions` ON `ErrorPage_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `RedirectorPage_versions` ON `RedirectorPage_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `VirtualPage_versions` ON `VirtualPage_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `UserDefinedForm_versions` ON `UserDefinedForm_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `SubscribeForm_versions` ON `SubscribeForm_versions`.ID = `SiteTree_lang_versions`.OriginalLangID WHERE (`SiteTree_versions`.SubsiteID IN (0)) AND (`SiteTree_lang_versions`.Lang = 'pt') AND (`SiteTree_versions`.`WasPublished` = 1 AND `URLSegment` = 'home') ORDER BY `LastEdited` DESC, `SiteTree_versions`.`WasPublished` LIMIT 1,256)
Line 104 of DB.php
* DB::query(SELECT `SiteTree_versions`.RecordID FROM `SiteTree_lang_versions` INNER JOIN `SiteTree_versions` ON `SiteTree_lang_versions`.OriginalLangID = `SiteTree_versions`.ID LEFT JOIN `GhostPage_versions` ON `GhostPage_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `BlogEntry_versions` ON `BlogEntry_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `BlogHolder_versions` ON `BlogHolder_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `Forum_versions` ON `Forum_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `ForumHolder_versions` ON `ForumHolder_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `GameFlash_versions` ON `GameFlash_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `GoogleCustomSearch_versions` ON `GoogleCustomSearch_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `ErrorPage_versions` ON `ErrorPage_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `RedirectorPage_versions` ON `RedirectorPage_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `VirtualPage_versions` ON `VirtualPage_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `UserDefinedForm_versions` ON `UserDefinedForm_versions`.ID = `SiteTree_lang_versions`.OriginalLangID LEFT JOIN `SubscribeForm_versions` ON `SubscribeForm_versions`.ID = `SiteTree_lang_versions`.OriginalLangID WHERE (`SiteTree_versions`.SubsiteID IN (0)) AND (`SiteTree_lang_versions`.Lang = 'pt') AND (`SiteTree_versions`.`WasPublished` = 1 AND `URLSegment` = 'home') ORDER BY `LastEdited` DESC, `SiteTree_versions`.`WasPublished` LIMIT 1)
Line 426 of SQLQuery.php
* SQLQuery->execute()
Line 106 of ModelAsController.php
* ModelAsController->findOldPage(home)
Line 47 of ModelAsController.php
* ModelAsController->getNestedController()
Line 25 of ModelAsController.php
* ModelAsController->handleRequest(HTTPRequest)
Line 34 of RootURLController.php
* RootURLController->handleRequest(HTTPRequest)
Line 277 of Director.php
* Director::handleRequest(HTTPRequest,Session)
Line 121 of Director.php
* Director::direct()
Line 115 of main.php

i18n does not work with 2.3.1. This is the goal for 2.3.2. For more information see http://open.silverstripe.com/ticket/3517

@willr: Is it possible that you mean: "Translatable" does not work with 2.3.1 ? That ticket you mention concerns Translatable.
At least if i18n itself has issues they seem not to be a major problem, i just developed a multilingual site with 2.3.1 using i18n (not translatable!) and it works as expected.

just checked my code, and i'm using only i18n::set_locale() but not i18n::set_default_lang().
You're sure you need set_default_lang()?

I remember coming across the same Error-accumulation.
Are you sure you updated your Database after setting the default lang? Setting this means, than i18n is enabled and therefore, a bunch of new tables has to be created in the database.

Bye,

Henning

I just got this error message with even touching i18n. I might have pressed the translation tab out of curiosity.

Fatal error: Cannot use string offset as an array in /homez.60/lasergra/www/SS/sapphire/core/i18n.php on line 859

CMS is now blocked because of this.