SQL Server不存在或访问被拒绝（对于以前有效的连接）

Question

I apologize in advance for how vague this question is. I had a connection string to SQL Server 2012 on a remote server from my work laptop using Visual Studio 2015 and it worked well for connecting to my database to populate asp:dropdownlists etc. on my web app as well as generating reports using SSRS.

That was last week, today I'm getting the error indicated in the title of this post. Below is my connection string minus the specific server name and ip address. Something changed between last Friday and today that this error is popping up.

Provider=SQLOLEDB.1;Data Source=[Server Name];Initial Catalog=[Database Name];Network Address=[Server IP Address]

I admittedly am at a loss as to how to troubleshoot this. I would endlessly appreciate a few leads as to what I can check out, whether there is some sort of log that tracks failed log ins, or some other means of finding out the source of the problem, or what changed.

Thank you so much in advance for helping a brand new programmer.

Answer 1

The problem could be any of the above problems, or a SQL Server configuration issue, or a network problem, or a permissions issue. The first thing I usually try is connecting with SQL Server Management Studio with the same settings. This will give a much more detailed message with specifics of what is failing. In short, all of the numbers in the error message are important and help pinpoint the real problem. You can also use https://msdn.microsoft.com/en-us/library/mt750266.aspx for some other techniques to diagnose/repair the issue.