Exception messages have not always evolved as behavior has evolved. Some exception messages are now wrong, while others are now unhelpful. Proposal:

• Review with a group of people making sure that messages are correct and deciding what to add or remove from the message. Avoid wordsmithing as a team since this is painful and slow.
• Focus on messages commonly seen and consider adding forward links.
• One person (e.g. @rowanmiller @roji) goes through and writes the messages
• PR review for tweaks

Updated process:

• Each @dotnet/efteam person will go through messages that they understand and check for content based on the checklist below.
  • This should not include wordsmithing or items in the style checklist--these will be done by one person per assembly
  • Each resource should be marked appropriately in the spreadsheet attached to the Teams channel
• Once this has been completed, we will go through the remaining resources (based on the spreadsheet) as a team

Content checklist:

• Does the message say what went wrong?
• Does it have a second sentence indicating what to do about it?
• Are we providing specific metadata names, ID values, etc. where helpful?
• Does it expose sensitive data without sensitive data logging enabled?
• Would a fwlink help?

Style checklist:

• Use {entityType}.{property/navigation}' rather than '{property/navigation}' of entity type '{entityType}'. Note that this will change the order of parameters, and so call sites will need to be updated.
• Specify attributes without single quotes and with the square brackets @smitpatel
• Be consistent about OnModelCreating as the terminology for fluent API @AndriySvyryd
• Use "navigation" rather than "navigation property" @AndriySvyryd
• Check usage of {foreignKey} and for correct quoting and use foreignKeyProperties where appropriate @AndriySvyryd
• Grammar, punctuation and casing @roji
• Be consistent about methods being formatted as 'Method' @roji
• Be consistent about types being formatted as 'Type'
• Make sure all "non blah" are spelled "non-blah" @roji
• Use "Entity Framework" when referring to EF @roji done @smitpatel
• Consistently use "context instance" instead of "context" or "DbContext" @roji
• Weak entity types should be referred to as entity types with a defining navigation @roji
• Shared entity types should be referred to as shared-type entity types @roji
• Is this still relevant? - "For ASP.NET WebForms bind to 'DbSet.ToList' or use Model Binding." @ajcvickers
• Replace "please report it" with "file an issue" and a fwlink to new issue @smitpatel
• Discuss whether null should be quoted and when (Exception message review #22519 (comment))

See also #22309, #22308, #22374

Specific messages to investigate:

• AnnotationNotFound - Can we use ToString or something similar to show the name of the object it was not found on? @AndriySvyryd
• CanConnectNotImplemented - Obsolete @roji
• AttemptToCreateEntityTypeBasedOnProxyClass Investigate what this means and try to be helpful. @smitpatel
• BadFilterDerivedType - Specify the root type @AndriySvyryd
• CannotConvertQueryableToEnumerableMethod - Consider adding some text indicating that this should never be hit @smitpatel
• NullTypeMappingInSqlTree should include the expression @smitpatel
• CircularDependency consider adding a fwlink to a docs page Document how circular dependency in data can be resolved EntityFramework.Docs#2619
• PoolingContextCtorError (Improve exception message: The DbContext of type cannot be pooled because it does not have a single public constructor #18573) @AndriySvyryd
• ConflictingForeignKeyAttributes can be obsoleted @AndriySvyryd
• DuplicateAnnotation - add ToString of annotatable @AndriySvyryd
• DuplicatePropertyInList - split into separate messages for each use case @AndriySvyryd
• ConverterBadType - Add quotes to the items in {allowed} @smitpatel
• DbSetIncorrectGenericType - review whether the passed in names make sense and correspond to the name used in the DbSet constructor @smitpatel
• EntityEqualityOnKeylessEntityNotSupported - specify operator @smitpatel
• EntityEqualitySubqueryWithCompositeKeyNotSupported - specify operator, add documenation on how to rewrite and add fwlink @smitpatel
• ErrorMaterializingValueInvalidCast, ErrorMaterializingValueNullReference - move to Relational @smitpatel
• EntityRequiresKey - add fwlink to keyless docs @smitpatel
• ConverterBadType - Add quotes to the items in {allowed} @smitpatel
• DuplicatePropertiesOnBase - consider rewording @roji