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by Jiří {x2} Činčura

Error “The operation could not be completed” or “Exception has been thrown by the target of an invocation." when opening LINQ to SQL file in VS2008

8 May 2008 2 mins LINQ, Visual Studio

Today I get error The operation could not be completed when I was trying to open *.dbml LINQ to SQL file. I have this developement environment in virtual machine and I did no installs or updates. Event Log also wasn’t saying anything that could help. First classic shoots like restart, cleaning all temps, caches etc. – nothing. Still same problem.

I’ve tried to add new dbml to project (in worst case, I was ready to copy to content of files, because build was OK). Heureka, designer opened like a charm. But, 😃 when I dropped some table on designer’s surface I got error Exception has been thrown by the target of an invocation.. Hmm, damn.

Thanks my paranoia I have backups of a lot of stuff, virtuals too. 1-2 hours of installing and I was back. When configuring my new-old machine everything worked fine. So I’ve installed some experimental stuff like Entity Framework beta, some VS updates required and added DDEX for Firebird. Just quick click-click-next-next. I opened the project and wanted to open dbml file, oh, the error was back again.

After this, I incidentally realised, that I’ve removed FirebirdClient assembly from GAC after installing DDEX. To make DDEX work I’ve installed 2.1 version, ’cause I have it built. But for testing Entity Framework support I’m using 2.5.x version and I was planning to add it later, ’cause I had no built assembly near my hands. Exactly this (removing FirebirdClient from GAC) I did few days ago, when I was debugging some reported issue. And that was the problem! How innocent and how devastating. 😄

Adding assembly back to GAC solved the problem. Hope this helps somebody. 😉 Wish I’ve found it sooner and saved time with copying and installing stuff.

Profile Picture Jiří Činčura is .NET, C# and Firebird expert. He's focused on data and business layers, language constructs, parallelism, databases and performance. He's Microsoft Most Valuable Professional and frequent speaker. You can read his articles, guides and tips and tricks at