290 posts tagged with ".NET"

dotnet ef, the command-line tools for Entity Framework Core, is usually installed once for the whole computer. Installed as a local tool instead, it's pinned to an exact version in a small file inside your repository, so every developer and every build machine runs the same version as the project's EF Core packages. This guide installs it that way with .NET 10, shows every command's real output, and adds the one package the tools need in your project.

Unable to create a 'DbContext' of type 'Dewiride.Inventory.Data.InventoryDbContext'. The exception 'Unable to resolve service for type 'Microsoft.EntityFrameworkCore.DbContextOptions`1[Dewiride.Inventory.Data.InventoryDbContext]' while attempting to activate 'Dewiride.Inventory.Data.InventoryDbContext'.' was thrown while attempting to create an instance. The useful part is the line printed just before it: the app's own startup code had failed, so EF Core's tools couldn't get the DbContext the normal way. Here's how I ran into it with a migrations bundle, why --connection didn't help, and the fix.

NU1608: Detected package version outside of dependency constraint: Pomelo.EntityFrameworkCore.MySql 9.0.0 requires Microsoft.EntityFrameworkCore.Relational (>= 9.0.0 && <= 9.0.999) but version Microsoft.EntityFrameworkCore.Relational 10.0.14 was resolved. The message spells out the problem: the newest Pomelo MySQL provider is built for EF Core 9, and the project runs EF Core 10. That isn't a version to nudge; it's a provider that doesn't support your EF Core yet.

dotnet package update --vulnerable is .NET 10's way to move vulnerable packages to a fixed version in one command. In my solution it printed error: Restore failed, then Unhandled exception: Specified method is not supported., and stopped. The crash message is misleading; the cause is documented: the command restores to do its work, and TreatWarningsAsErrors turned NuGet's own vulnerability warning into a restore error.

error NU1903: Warning As Error: Package 'Newtonsoft.Json' 12.0.3 has a known high severity vulnerability, https://github.com/advisories/GHSA-5crp-9r3c-p9vr NuGet's built-in audit found a published security advisory for a package version the project uses, and because warnings were errors, restore stopped. The fix is one version change. Getting there took me two failed attempts first, and both are worth knowing.

System.IO.IOException: Failed to bind to address http://127.0.0.1:5190: address already in use. The app is fine; the port isn't free. Something else, very often another copy of the same app, is already listening on it. Here's how I found what held the port, stopped it cleanly, and when to pick another port instead.

error IDE0044: Make field readonly appeared the first time I made the build check code style. The rule is right more often than not: the field was set once and never changed, so the compiler can promise that it never will. Here's what the rule checks, why it was an error rather than a hint, and the fix.

error NU1109: Detected package downgrade: Microsoft.EntityFrameworkCore.Relational from 10.0.12 to centrally defined 10.0.11. Update the centrally managed package version to a higher version. In a solution with Central Package Management and transitive pinning, the central file asked for an older version of a package than one of the dependencies needs. The two lines under the message show exactly who wants what.

error: NU1202: Package Microsoft.EntityFrameworkCore 11.0.0-rc.3.26522.148 is not compatible with net10.0 (.NETCoreApp,Version=v10.0). Package Microsoft.EntityFrameworkCore 11.0.0-rc.3.26522.148 supports: net11.0 (.NETCoreApp,Version=v11.0) The package was fine, and so was the project; they were made for different .NET versions. The message names both, and dotnet package add refused before it changed anything.

error CS0246: The type or namespace name 'Dewiride' could not be found (are you missing a using directive or an assembly reference?) The compiler ends the message with a question, and it's a good one: those are the two usual causes. The name in quotes and the line number tell you which one you have. Here are both, from the same .NET 10 project, and the fix for each.