Entity Framework Error. The underlying provider failed on Open Cannot attach the file

Question

I have a simple asp.net mvc project which should create a database on the app data folder, but I get the error below

{"The underlying provider failed on Open."} {"Cannot attach the file 'F:\GoogleDriveSync\products_WB0R5L90S\MVC5_Full_VersionCapatech\Inspinia_MVC5\App_Data\TokenCacheDataContext.mdf' as database 'TokenCacheDataContext'.

The code is based on this github project https://github.com/andrewconnell/azadaspnetmvcauth

And my code is as follows: EfAdalTokenCache

public class EfAdalTokenCache : TokenCache
    {
        private TokenCacheDataContext db = new TokenCacheDataContext();
        string User;
        private PerUserWebCache Cache;

        // constructor
        public EfAdalTokenCache(string user)
        {
            // associate the cache to the current user of the web app
            User = user;

            this.AfterAccess = AfterAccessNotification;
            this.BeforeAccess = BeforeAccessNotification;
            this.BeforeWrite = BeforeWriteNotification;

            // look up the entry in the DB
            Cache = db.PerUserCacheList.FirstOrDefault(c => c.WebUserUniqueId == User);
            // place the entry in memory
            this.Deserialize((Cache == null) ? null : Cache.CacheBits);
        }

        // clean up the DB
        public override void Clear()
        {
            base.Clear();
            foreach (var cacheEntry in db.PerUserCacheList)
                db.PerUserCacheList.Remove(cacheEntry);
            db.SaveChanges();
        }

        // Notification raised before ADAL accesses the cache.
        // This is your chance to update the in-memory copy from the DB, if the in-memory version is stale
        void BeforeAccessNotification(TokenCacheNotificationArgs args)
        {
            if (Cache == null)
            {
                // first time access
                Cache = db.PerUserCacheList.FirstOrDefault(c => c.WebUserUniqueId == User);
            }
            else
            {   // retrieve last write from the DB
                var status = from e in db.PerUserCacheList
                             where (e.WebUserUniqueId == User)
                             select new
                             {
                                 LastWrite = e.LastWrite
                             };
                // if the in-memory copy is older than the persistent copy
                if (status.First().LastWrite > Cache.LastWrite)
                //// read from from storage, update in-memory copy 
                {
                    Cache = db.PerUserCacheList.FirstOrDefault(c => c.WebUserUniqueId == User);
                }
            }


            this.Deserialize((Cache == null) ? null : Cache.CacheBits);
        }
        // Notification raised after ADAL accessed the cache.
        // If the HasStateChanged flag is set, ADAL changed the content of the cache
        void AfterAccessNotification(TokenCacheNotificationArgs args)
        {
            // if state changed
            if (this.HasStateChanged)
            {
                Cache = new PerUserWebCache
                {
                    WebUserUniqueId = User,
                    CacheBits = this.Serialize(),
                    LastWrite = DateTime.Now
                };
                //// update the DB and the lastwrite                
                db.Entry(Cache).State = Cache.EntryId == 0 ? EntityState.Added : EntityState.Modified;
                db.SaveChanges();
                this.HasStateChanged = false;
            }
        }
        void BeforeWriteNotification(TokenCacheNotificationArgs args)
        {
            // if you want to ensure that no concurrent write take place, use this notification to place a lock on the entry
        }
    }

Error is thrown above on the

Cache = db.PerUserCacheList.FirstOrDefault(c => c.WebUserUniqueId == User);

Global.asax

 protected void Application_Start()
        {

            AreaRegistration.RegisterAllAreas();
            FilterConfig.RegisterGlobalFilters(GlobalFilters.Filters);
            RouteConfig.RegisterRoutes(RouteTable.Routes);
            BundleConfig.RegisterBundles(BundleTable.Bundles);

            Database.SetInitializer(new TokenCacheInitializer());
        }

TokenCacheInitializer

 public class TokenCacheInitializer : System.Data.Entity.DropCreateDatabaseIfModelChanges<TokenCacheDataContext>
    {
    }

TokenCacheDataContext

public class TokenCacheDataContext : DbContext
    {
        public TokenCacheDataContext()
          : base("TokenCacheDataContext")
        { }

        public DbSet<PerUserWebCache> PerUserCacheList { get; set; }

        protected override void OnModelCreating(DbModelBuilder modelBuilder)
        {
            modelBuilder.Conventions.Remove<PluralizingTableNameConvention>();
        }
    }

Model PerUserWebCache

public class PerUserWebCache
    {
        [Key]
        public int EntryId { get; set; }
        public string WebUserUniqueId { get; set; }
        public byte[] CacheBits { get; set; }
        public DateTime LastWrite { get; set; }
    }

Answer 1

Please check this link

Also check your connection string.

Open the "Developer Command Prompt for Visual Studio" under your start/programs menu you need admin previleges. Run the following commands:

sqllocaldb.exe stop v11.0

sqllocaldb.exe delete v11.0

After that, Start your MVC Application