diff --git a/amanuensis/backend/__init__.py b/amanuensis/backend/__init__.py
index e69de29..e0c9365 100644
--- a/amanuensis/backend/__init__.py
+++ b/amanuensis/backend/__init__.py
@@ -0,0 +1,9 @@
+import amanuensis.backend.article as artiq
+import amanuensis.backend.character as charq
+import amanuensis.backend.index as indq
+import amanuensis.backend.lexicon as lexiq
+import amanuensis.backend.membership as memq
+import amanuensis.backend.post as postq
+import amanuensis.backend.user as userq
+
+__all__ = ["artiq", "charq", "indq", "lexiq", "memq", "postq", "userq"]
diff --git a/amanuensis/backend/article.py b/amanuensis/backend/article.py
index 973c123..187e9d0 100644
--- a/amanuensis/backend/article.py
+++ b/amanuensis/backend/article.py
@@ -7,7 +7,7 @@ from typing import Optional
 from sqlalchemy import select
 
 from amanuensis.db import *
-from amanuensis.errors import ArgumentError
+from amanuensis.errors import ArgumentError, BackendArgumentTypeError
 
 
 def create(
@@ -21,11 +21,11 @@ def create(
     """
     # Verify argument types are correct
     if not isinstance(lexicon_id, int):
-        raise ArgumentError("lexicon_id")
+        raise BackendArgumentTypeError(int, lexicon_id=lexicon_id)
     if not isinstance(user_id, int):
-        raise ArgumentError("user_id")
+        raise BackendArgumentTypeError(int, user_id=user_id)
     if character_id is not None and not isinstance(character_id, int):
-        raise ArgumentError("character_id")
+        raise BackendArgumentTypeError(int, character_id=character_id)
 
     # Check that the user is a member of this lexicon
     mem: Membership = db(
diff --git a/amanuensis/backend/character.py b/amanuensis/backend/character.py
index 1b87b3b..01f5804 100644
--- a/amanuensis/backend/character.py
+++ b/amanuensis/backend/character.py
@@ -7,7 +7,7 @@ from typing import Optional
 from sqlalchemy import select, func
 
 from amanuensis.db import *
-from amanuensis.errors import ArgumentError
+from amanuensis.errors import ArgumentError, BackendArgumentTypeError
 
 
 def create(
@@ -22,13 +22,13 @@ def create(
     """
     # Verify argument types are correct
     if not isinstance(lexicon_id, int):
-        raise ArgumentError("lexicon_id")
+        raise BackendArgumentTypeError(int, lexicon_id=lexicon_id)
     if not isinstance(user_id, int):
-        raise ArgumentError("user_id")
+        raise BackendArgumentTypeError(int, user_id=user_id)
     if not isinstance(name, str):
-        raise ArgumentError("name")
+        raise BackendArgumentTypeError(str, name=name)
     if signature is not None and not isinstance(signature, str):
-        raise ArgumentError("signature")
+        raise BackendArgumentTypeError(str, signature=signature)
 
     # Verify character name is valid
     if not name.strip():
diff --git a/amanuensis/backend/index.py b/amanuensis/backend/index.py
index 7f108ec..bfd259c 100644
--- a/amanuensis/backend/index.py
+++ b/amanuensis/backend/index.py
@@ -6,7 +6,7 @@ import re
 from typing import Optional
 
 from amanuensis.db import DbContext, ArticleIndex, IndexType
-from amanuensis.errors import ArgumentError
+from amanuensis.errors import ArgumentError, BackendArgumentTypeError
 
 
 def create(
@@ -23,17 +23,17 @@ def create(
     """
     # Verify argument types are correct
     if not isinstance(lexicon_id, int):
-        raise ArgumentError("lexicon_id")
+        raise BackendArgumentTypeError(int, lexicon_id=lexicon_id)
     if not isinstance(index_type, IndexType):
-        raise ArgumentError("index_type")
+        raise BackendArgumentTypeError(IndexType, index_type=index_type)
     if not isinstance(pattern, str):
-        raise ArgumentError("pattern")
+        raise BackendArgumentTypeError(str, pattern=pattern)
     if not isinstance(logical_order, int):
-        raise ArgumentError("logical_order")
+        raise BackendArgumentTypeError(int, logical_order=logical_order)
     if not isinstance(display_order, int):
-        raise ArgumentError("display_order")
+        raise BackendArgumentTypeError(int, display_order=display_order)
     if capacity is not None and not isinstance(capacity, int):
-        raise ArgumentError("capacity")
+        raise BackendArgumentTypeError(int, capacity=capacity)
 
     # Verify the pattern is valid for the index type:
     if index_type == IndexType.CHAR:
diff --git a/amanuensis/backend/lexicon.py b/amanuensis/backend/lexicon.py
index 5efd406..ff83b34 100644
--- a/amanuensis/backend/lexicon.py
+++ b/amanuensis/backend/lexicon.py
@@ -8,7 +8,7 @@ from typing import Sequence, Optional
 from sqlalchemy import select, func
 
 from amanuensis.db import DbContext, Lexicon, Membership
-from amanuensis.errors import ArgumentError
+from amanuensis.errors import ArgumentError, BackendArgumentTypeError
 
 
 RE_ALPHANUM_DASH_UNDER = re.compile(r"^[A-Za-z0-9-_]*$")
@@ -25,7 +25,7 @@ def create(
     """
     # Verify name
     if not isinstance(name, str):
-        raise ArgumentError("Lexicon name must be a string")
+        raise BackendArgumentTypeError(str, name=name)
     if not name.strip():
         raise ArgumentError("Lexicon name must not be blank")
     if not RE_ALPHANUM_DASH_UNDER.match(name):
@@ -34,12 +34,12 @@ def create(
         )
 
     # Verify title
-    if title is not None and not isinstance(name, str):
-        raise ArgumentError("Lexicon name must be a string")
+    if title is not None and not isinstance(title, str):
+        raise BackendArgumentTypeError(str, title=title)
 
     # Verify prompt
     if not isinstance(prompt, str):
-        raise ArgumentError("Lexicon prompt must be a string")
+        raise BackendArgumentTypeError(str, prompt=prompt)
 
     # Query the db to make sure the lexicon name isn't taken
     if db(select(func.count(Lexicon.id)).where(Lexicon.name == name)).scalar() > 0:
@@ -55,11 +55,6 @@ def create(
     return new_lexicon
 
 
-def from_name(db: DbContext, name: str) -> Lexicon:
-    """Get a lexicon by its name."""
-    return db(select(Lexicon).where(Lexicon.name == name)).scalar_one()
-
-
 def get_all(db: DbContext) -> Sequence[Lexicon]:
     """Get all lexicons."""
     return db(select(Lexicon)).scalars()
@@ -75,3 +70,8 @@ def get_joined(db: DbContext, user_id: int) -> Sequence[Lexicon]:
 def get_public(db: DbContext) -> Sequence[Lexicon]:
     """Get all publicly visible lexicons."""
     return db(select(Lexicon).where(Lexicon.public == True)).scalars()
+
+
+def try_from_name(db: DbContext, name: str) -> Optional[Lexicon]:
+    """Get a lexicon by its name, or None if no such lexicon was found."""
+    return db(select(Lexicon).where(Lexicon.name == name)).scalar_one_or_none()
diff --git a/amanuensis/backend/membership.py b/amanuensis/backend/membership.py
index 5e9af13..baddcdd 100644
--- a/amanuensis/backend/membership.py
+++ b/amanuensis/backend/membership.py
@@ -6,7 +6,7 @@ from sqlalchemy import select, func
 
 from amanuensis.db import DbContext, Membership
 from amanuensis.db.models import Lexicon
-from amanuensis.errors import ArgumentError
+from amanuensis.errors import ArgumentError, BackendArgumentTypeError
 
 
 def create(
@@ -20,11 +20,11 @@ def create(
     """
     # Verify argument types are correct
     if not isinstance(user_id, int):
-        raise ArgumentError("user_id")
+        raise BackendArgumentTypeError(int, user_id=user_id)
     if not isinstance(lexicon_id, int):
-        raise ArgumentError("lexicon_id")
+        raise BackendArgumentTypeError(int, lexicon_id=lexicon_id)
     if not isinstance(is_editor, bool):
-        raise ArgumentError("is_editor")
+        raise BackendArgumentTypeError(bool, is_editor=is_editor)
 
     # Verify user has not already joined lexicon
     if (
diff --git a/amanuensis/backend/post.py b/amanuensis/backend/post.py
index 0a6373f..8a4d59d 100644
--- a/amanuensis/backend/post.py
+++ b/amanuensis/backend/post.py
@@ -8,7 +8,7 @@ from sqlalchemy import select
 
 from amanuensis.db import DbContext, Post
 from amanuensis.db.models import Lexicon
-from amanuensis.errors import ArgumentError
+from amanuensis.errors import ArgumentError, BackendArgumentTypeError
 
 
 def create(
@@ -23,15 +23,15 @@ def create(
 
     # Verify lexicon id
     if not isinstance(lexicon_id, int):
-        raise ArgumentError("Lexicon id must be an integer.")
+        raise BackendArgumentTypeError(int, lexicon_id=lexicon_id)
 
     # Verify user_id
-    if not (isinstance(user_id, int) or user_id is None):
-        raise ArgumentError("User id must be an integer.")
+    if user_id is not None and not isinstance(user_id, int):
+        raise BackendArgumentTypeError(int, user_id=user_id)
 
     # Verify body
     if not isinstance(body, str):
-        raise ArgumentError("Post body must be a string.")
+        raise BackendArgumentTypeError(str, body=body)
     if not body.strip():
         raise ArgumentError("Post body cannot be empty.")
 
diff --git a/amanuensis/backend/user.py b/amanuensis/backend/user.py
index 1283fb2..e07e315 100644
--- a/amanuensis/backend/user.py
+++ b/amanuensis/backend/user.py
@@ -10,7 +10,7 @@ from sqlalchemy import select, func, update
 from werkzeug.security import generate_password_hash, check_password_hash
 
 from amanuensis.db import DbContext, User
-from amanuensis.errors import ArgumentError
+from amanuensis.errors import ArgumentError, BackendArgumentTypeError
 
 
 RE_NO_LETTERS = re.compile(r"^[0-9-_]*$")
@@ -30,7 +30,7 @@ def create(
     """
     # Verify username
     if not isinstance(username, str):
-        raise ArgumentError("Username must be a string")
+        raise BackendArgumentTypeError(str, username=username)
     if len(username) < 3 or len(username) > 32:
         raise ArgumentError("Username must be between 3 and 32 characters")
     if RE_NO_LETTERS.match(username):
@@ -42,18 +42,18 @@ def create(
 
     # Verify password
     if not isinstance(password, str):
-        raise ArgumentError("Password must be a string")
+        raise BackendArgumentTypeError(str, password=password)
 
     # Verify display name
     if display_name is not None and not isinstance(display_name, str):
-        raise ArgumentError("Display name must be a string")
+        raise BackendArgumentTypeError(str, display_name=display_name)
     # If display name is not provided, use the username
     if not display_name or not display_name.strip():
         display_name = username
 
     # Verify email
     if not isinstance(email, str):
-        raise ArgumentError("Email must be a string")
+        raise BackendArgumentTypeError(str, email=email)
 
     # Query the db to make sure the username isn't taken
     if db(select(func.count(User.id)).where(User.username == username)).scalar() > 0:
@@ -71,24 +71,6 @@ def create(
     return new_user
 
 
-def from_id(db: DbContext, user_id: int) -> Optional[User]:
-    """
-    Get a user by the user's id.
-    Returns None if no user was found.
-    """
-    user: User = db(select(User).where(User.id == user_id)).scalar_one_or_none()
-    return user
-
-
-def from_username(db: DbContext, username: str) -> Optional[User]:
-    """
-    Get a user by the user's username.
-    Returns None if no user was found.
-    """
-    user: User = db(select(User).where(User.username == username)).scalar_one_or_none()
-    return user
-
-
 def get_all(db: DbContext) -> Sequence[User]:
     """Get all users."""
     return db(select(User)).scalars()
@@ -109,6 +91,16 @@ def password_check(db: DbContext, username: str, password: str) -> bool:
     return check_password_hash(user_password_hash, password)
 
 
+def try_from_id(db: DbContext, user_id: int) -> Optional[User]:
+    """Get a user by the user's id, or None is no such user was found."""
+    return db(select(User).where(User.id == user_id)).scalar_one_or_none()
+
+
+def try_from_username(db: DbContext, username: str) -> Optional[User]:
+    """Get a user by the user's username, or None is no such user was found."""
+    return db(select(User).where(User.username == username)).scalar_one_or_none()
+
+
 def update_logged_in(db: DbContext, username: str) -> None:
     """Bump the value of the last_login column for a user."""
     db(
diff --git a/amanuensis/cli/lexicon.py b/amanuensis/cli/lexicon.py
index 2d580d2..0c0e3c1 100644
--- a/amanuensis/cli/lexicon.py
+++ b/amanuensis/cli/lexicon.py
@@ -2,9 +2,7 @@ import logging
 
 from sqlalchemy import update
 
-import amanuensis.backend.lexicon as lexiq
-import amanuensis.backend.membership as memq
-import amanuensis.backend.user as userq
+from amanuensis.backend import lexiq, memq, userq
 from amanuensis.db import DbContext, Lexicon
 
 from .helpers import add_argument
@@ -24,9 +22,12 @@ def command_add(args) -> int:
     Add a user to a lexicon.
     """
     db: DbContext = args.get_db()
-    lexicon = lexiq.from_name(db, args.lexicon)
-    user = userq.from_username(db, args.user)
-    assert user is not None
+    lexicon = lexiq.try_from_name(db, args.lexicon)
+    if not lexicon:
+        raise ValueError("Lexicon does not exist")
+    user = userq.try_from_username(db, args.user)
+    if not user:
+        raise ValueError("User does not exist")
     memq.create(db, user.id, lexicon.id, args.editor)
     LOG.info(f"Added {args.user} to lexicon {args.lexicon}")
     return 0
diff --git a/amanuensis/cli/user.py b/amanuensis/cli/user.py
index 79518eb..9506e09 100644
--- a/amanuensis/cli/user.py
+++ b/amanuensis/cli/user.py
@@ -1,7 +1,7 @@
 import logging
 from typing import Optional
 
-import amanuensis.backend.user as userq
+from amanuensis.backend import userq
 from amanuensis.db import DbContext, User
 
 from .helpers import add_argument
@@ -29,7 +29,7 @@ def command_create(args) -> int:
 def command_promote(args) -> int:
     """Make a user a site admin."""
     db: DbContext = args.get_db()
-    user: Optional[User] = userq.from_username(db, args.username)
+    user: Optional[User] = userq.try_from_username(db, args.username)
     if user is None:
         args.parser.error("User not found")
         return -1
@@ -46,7 +46,7 @@ def command_promote(args) -> int:
 def command_demote(args):
     """Revoke a user's site admin status."""
     db: DbContext = args.get_db()
-    user: Optional[User] = userq.from_username(db, args.username)
+    user: Optional[User] = userq.try_from_username(db, args.username)
     if user is None:
         args.parser.error("User not found")
         return -1
diff --git a/amanuensis/errors.py b/amanuensis/errors.py
index b6a9145..7c35ee1 100644
--- a/amanuensis/errors.py
+++ b/amanuensis/errors.py
@@ -4,8 +4,21 @@ Submodule of custom exception types
 
 
 class AmanuensisError(Exception):
-    """Base class for exceptions in amanuensis"""
+    """Base class for exceptions in Amanuensis"""
 
 
 class ArgumentError(AmanuensisError):
-    """An internal call was made with invalid arguments"""
+    """An internal call was made with invalid arguments."""
+
+
+class BackendArgumentTypeError(ArgumentError):
+    """
+    A call to a backend function was made with a value of an invalid type for the parameter.
+    Specify the invalid parameter and value as a kwarg.
+    """
+    def __init__(self, obj_type, **kwarg):
+        if not kwarg:
+            raise ValueError("Missing kwarg")
+        param, value = next(iter(kwarg.items()))
+        msg = f"Expected {param} of type {obj_type}, got {type(value)}"
+        super().__init__(msg)
diff --git a/amanuensis/server/__init__.py b/amanuensis/server/__init__.py
index 2f73815..5ffd770 100644
--- a/amanuensis/server/__init__.py
+++ b/amanuensis/server/__init__.py
@@ -2,16 +2,33 @@ from datetime import datetime, timezone
 import json
 import os
 
-from flask import Flask, g
+from flask import Flask, g, url_for
 
-import amanuensis.backend.lexicon
-import amanuensis.backend.user
+from amanuensis.backend import lexiq, userq, memq
 from amanuensis.config import AmanuensisConfig, CommandLineConfig
 from amanuensis.db import DbContext
+from amanuensis.parser import filesafe_title
 import amanuensis.server.auth as auth
 import amanuensis.server.home as home
 
 
+def date_format(dt: datetime, formatstr="%Y-%m-%d %H:%M:%S%z") -> str:
+    """Convert datetime to human-readable string"""
+    if dt is None:
+        return "never"
+    # Cast db time to UTC, then convert to local timezone
+    adjusted = dt.replace(tzinfo=timezone.utc).astimezone()
+    return adjusted.strftime(formatstr)
+
+
+def article_link(title):
+    """Get the url for a lexicon by its title"""
+    return url_for(
+        'lexicon.article',
+        name=g.lexicon.name,
+        title=filesafe_title(title))
+
+
 def get_app(
     config: AmanuensisConfig,
     db: DbContext = None,
@@ -49,20 +66,12 @@ def get_app(
     app.teardown_appcontext(db_teardown)
 
     # Configure jinja options
-    app.jinja_options.update(trim_blocks=True, lstrip_blocks=True)
-
-    def date_format(dt: datetime, formatstr="%Y-%m-%d %H:%M:%S%z") -> str:
-        if dt is None:
-            return "never"
-        # Cast db time to UTC, then convert to local timezone
-        adjusted = dt.replace(tzinfo=timezone.utc).astimezone()
-        return adjusted.strftime(formatstr)
-
-    app.template_filter("date")(date_format)
-
     def include_backend():
-        return {"db": db, "lexiq": amanuensis.backend.lexicon, "userq": amanuensis.backend.user}
+        return {"db": db, "lexiq": lexiq, "userq": userq, "memq": memq}
 
+    app.jinja_options.update(trim_blocks=True, lstrip_blocks=True)
+    app.template_filter("date")(date_format)
+    app.template_filter("articlelink")(article_link)
     app.context_processor(include_backend)
 
     # Set up Flask-Login
diff --git a/amanuensis/server/auth/__init__.py b/amanuensis/server/auth/__init__.py
index f8fc748..4cd049b 100644
--- a/amanuensis/server/auth/__init__.py
+++ b/amanuensis/server/auth/__init__.py
@@ -17,7 +17,7 @@ from flask_login import (
     LoginManager,
 )
 
-import amanuensis.backend.user as userq
+from amanuensis.backend import userq
 from amanuensis.db import User
 
 from .forms import LoginForm
@@ -39,7 +39,7 @@ def get_login_manager() -> LoginManager:
             user_id = int(user_id_str)
         except:
             return None
-        return userq.from_id(g.db, user_id)
+        return userq.try_from_id(g.db, user_id)
 
     login_manager.user_loader(load_user)
 
@@ -58,7 +58,7 @@ def login():
     # POST with valid data
     username: str = form.username.data
     password: str = form.password.data
-    user: User = userq.from_username(g.db, username)
+    user: User = userq.try_from_username(g.db, username)
     if not user or not userq.password_check(g.db, username, password):
         # Bad creds
         flash("Login not recognized")
diff --git a/amanuensis/server/home/__init__.py b/amanuensis/server/home/__init__.py
index c2608b3..6103e88 100644
--- a/amanuensis/server/home/__init__.py
+++ b/amanuensis/server/home/__init__.py
@@ -1,7 +1,6 @@
 from flask import Blueprint, render_template, g
 
-import amanuensis.backend.user as userq
-import amanuensis.backend.lexicon as lexiq
+from amanuensis.backend import userq, lexiq
 
 # from .forms import LexiconCreateForm
 
diff --git a/tests/backend/test_article.py b/tests/backend/test_article.py
index 7dafe02..269a898 100644
--- a/tests/backend/test_article.py
+++ b/tests/backend/test_article.py
@@ -1,9 +1,9 @@
 import pytest
 import time
 
-from amanuensis.db import DbContext
-from amanuensis.db.models import Character, Lexicon, User
-import amanuensis.backend.article as artiq
+from amanuensis.backend import artiq
+from amanuensis.db import DbContext, Character, Lexicon, User
+
 from amanuensis.errors import ArgumentError
 from tests.conftest import ObjectFactory
 
diff --git a/tests/backend/test_character.py b/tests/backend/test_character.py
index dc50302..bf0bb95 100644
--- a/tests/backend/test_character.py
+++ b/tests/backend/test_character.py
@@ -1,8 +1,8 @@
 import pytest
 
+from amanuensis.backend import charq
 from amanuensis.db import *
-import amanuensis.backend.character as charq
-from amanuensis.errors import ArgumentError
+from amanuensis.errors import ArgumentError, BackendArgumentTypeError
 
 
 def test_create_character(db: DbContext, lexicon_with_editor, make):
@@ -20,13 +20,13 @@ def test_create_character(db: DbContext, lexicon_with_editor, make):
     kwargs: dict
 
     # Bad argument types
-    with pytest.raises(ArgumentError):
+    with pytest.raises(BackendArgumentTypeError):
         kwargs = {**defaults, "name": b"bytestring"}
         charq.create(**kwargs)
-    with pytest.raises(ArgumentError):
+    with pytest.raises(BackendArgumentTypeError):
         kwargs = {**defaults, "name": None}
         charq.create(**kwargs)
-    with pytest.raises(ArgumentError):
+    with pytest.raises(BackendArgumentTypeError):
         kwargs = {**defaults, "signature": b"bytestring"}
         charq.create(**kwargs)
 
diff --git a/tests/backend/test_index.py b/tests/backend/test_index.py
index c5a2ac7..47128d4 100644
--- a/tests/backend/test_index.py
+++ b/tests/backend/test_index.py
@@ -1,8 +1,8 @@
 from amanuensis.db.models import IndexType
 import pytest
 
-import amanuensis.backend.index as indq
-from amanuensis.db import DbContext, Lexicon, User
+from amanuensis.backend import indq
+from amanuensis.db import DbContext, Lexicon
 
 from amanuensis.errors import ArgumentError
 
diff --git a/tests/backend/test_lexicon.py b/tests/backend/test_lexicon.py
index b2f07c9..dbbb904 100644
--- a/tests/backend/test_lexicon.py
+++ b/tests/backend/test_lexicon.py
@@ -3,9 +3,9 @@ import time
 
 import pytest
 
-import amanuensis.backend.lexicon as lexiq
+from amanuensis.backend import lexiq
 from amanuensis.db import DbContext, Lexicon, User
-from amanuensis.errors import ArgumentError
+from amanuensis.errors import ArgumentError, BackendArgumentTypeError
 from tests.conftest import ObjectFactory
 
 
@@ -20,7 +20,7 @@ def test_create_lexicon(db: DbContext):
     kwargs: dict
 
     # Test name constraints
-    with pytest.raises(ArgumentError):
+    with pytest.raises(BackendArgumentTypeError):
         kwargs = {**defaults, "name": None}
         lexiq.create(**kwargs)
     with pytest.raises(ArgumentError):
@@ -58,8 +58,8 @@ def test_lexicon_from(db: DbContext, make: ObjectFactory):
     """Test lexiq.from_*."""
     lexicon1: Lexicon = make.lexicon()
     lexicon2: Lexicon = make.lexicon()
-    assert lexiq.from_name(db, lexicon1.name) == lexicon1
-    assert lexiq.from_name(db, lexicon2.name) == lexicon2
+    assert lexiq.try_from_name(db, lexicon1.name) == lexicon1
+    assert lexiq.try_from_name(db, lexicon2.name) == lexicon2
 
 
 def test_get_lexicon(db: DbContext, make: ObjectFactory):
diff --git a/tests/backend/test_membership.py b/tests/backend/test_membership.py
index d6a0637..f62d6c1 100644
--- a/tests/backend/test_membership.py
+++ b/tests/backend/test_membership.py
@@ -2,9 +2,9 @@ import pytest
 
 from sqlalchemy import select
 
+from amanuensis.backend import memq
 from amanuensis.db import *
 from amanuensis.errors import ArgumentError
-import amanuensis.backend.membership as memq
 
 
 def test_create_membership(db: DbContext, make):
diff --git a/tests/backend/test_post.py b/tests/backend/test_post.py
index 773b705..289e989 100644
--- a/tests/backend/test_post.py
+++ b/tests/backend/test_post.py
@@ -1,9 +1,9 @@
 import pytest
 
+from amanuensis.backend import postq
 from amanuensis.db import DbContext
-import amanuensis.backend.post as postq
 
-from amanuensis.errors import ArgumentError
+from amanuensis.errors import ArgumentError, BackendArgumentTypeError
 
 
 def test_create_post(db: DbContext, lexicon_with_editor):
@@ -20,19 +20,16 @@ def test_create_post(db: DbContext, lexicon_with_editor):
     kwargs: dict
 
     # ids are integers
-    with pytest.raises(ArgumentError):
+    with pytest.raises(BackendArgumentTypeError):
         kwargs = {**defaults, "user_id": "zero"}
         postq.create(**kwargs)
-    with pytest.raises(ArgumentError):
+    with pytest.raises(BackendArgumentTypeError):
         kwargs = {**defaults, "lexicon_id": "zero"}
         postq.create(**kwargs)
 
     # empty arguments don't work
-    with pytest.raises(ArgumentError):
-        kwargs = {**defaults, "lexicon_id": ""}
-        postq.create(**kwargs)
-    with pytest.raises(ArgumentError):
-        kwargs = {**defaults, "user_id": ""}
+    with pytest.raises(BackendArgumentTypeError):
+        kwargs = {**defaults, "lexicon_id": None}
         postq.create(**kwargs)
     with pytest.raises(ArgumentError):
         kwargs = {**defaults, "body": ""}
diff --git a/tests/backend/test_user.py b/tests/backend/test_user.py
index e5fc571..6cf8f88 100644
--- a/tests/backend/test_user.py
+++ b/tests/backend/test_user.py
@@ -2,9 +2,9 @@ import os
 
 import pytest
 
-import amanuensis.backend.user as userq
+from amanuensis.backend import userq
 from amanuensis.db import DbContext, User
-from amanuensis.errors import ArgumentError
+from amanuensis.errors import ArgumentError, BackendArgumentTypeError
 
 
 def test_create_user(db: DbContext):
@@ -33,7 +33,7 @@ def test_create_user(db: DbContext):
         userq.create(**kwargs)
 
     # No password
-    with pytest.raises(ArgumentError):
+    with pytest.raises(BackendArgumentTypeError):
         kwargs = {**defaults, "password": None}
         userq.create(**kwargs)
 
@@ -57,10 +57,10 @@ def test_user_from(db: DbContext, make):
     """Test userq.from_*."""
     user1: User = make.user()
     user2: User = make.user()
-    assert userq.from_id(db, user1.id) == user1
-    assert userq.from_username(db, user1.username) == user1
-    assert userq.from_id(db, user2.id) == user2
-    assert userq.from_username(db, user2.username) == user2
+    assert userq.try_from_id(db, user1.id) == user1
+    assert userq.try_from_username(db, user1.username) == user1
+    assert userq.try_from_id(db, user2.id) == user2
+    assert userq.try_from_username(db, user2.username) == user2
 
 
 def test_user_password(db: DbContext, make):
diff --git a/tests/conftest.py b/tests/conftest.py
index 2dccf33..203da40 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -10,10 +10,7 @@ from bs4 import BeautifulSoup
 from flask.testing import FlaskClient
 from sqlalchemy.orm.session import close_all_sessions
 
-import amanuensis.backend.character as charq
-import amanuensis.backend.lexicon as lexiq
-import amanuensis.backend.membership as memq
-import amanuensis.backend.user as userq
+from amanuensis.backend import charq, lexiq, memq, userq
 from amanuensis.config import AmanuensisConfig
 from amanuensis.db import DbContext, User, Lexicon, Membership, Character
 from amanuensis.server import get_app
@@ -45,7 +42,7 @@ class UserClient:
 
     def login(self, client: FlaskClient):
         """Log the user in."""
-        user: Optional[User] = userq.from_id(self.db, self.user_id)
+        user: Optional[User] = userq.try_from_id(self.db, self.user_id)
         assert user is not None
 
         # Set the user's password so we know what it is later