diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index a026de6ff3..9147f6e825 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -39,7 +39,7 @@ repos:
     additional_dependencies: [pyyaml]
 
 - repo: https://github.com/astral-sh/ruff-pre-commit
-  rev: v0.0.277
+  rev: v0.0.281
   hooks:
   - id: ruff
     args: ["--fix", "--show-fixes"]
@@ -74,6 +74,6 @@ repos:
 
 
 - repo: https://github.com/asottile/pyupgrade
-  rev: v3.9.0
+  rev: v3.10.1
   hooks:
   - id: pyupgrade
diff --git a/dev/generate-kernel-signatures.py b/dev/generate-kernel-signatures.py
index 8a7479bd93..47a010452f 100644
--- a/dev/generate-kernel-signatures.py
+++ b/dev/generate-kernel-signatures.py
@@ -130,7 +130,7 @@ def include_kernels_h(specification):
         "w",
     ) as header:
         header.write(
-            """// AUTO GENERATED ON {0}
+            f"""// AUTO GENERATED ON {reproducible_datetime()}
 // DO NOT EDIT BY HAND!
 //
 // To regenerate file, run
@@ -146,9 +146,7 @@ def include_kernels_h(specification):
 
 extern "C" {{
 
-""".format(
-                reproducible_datetime()
-            )
+"""
         )
         for spec in specification["kernels"]:
             for childfunc in spec["specializations"]:
@@ -217,7 +215,7 @@ def kernel_signatures_py(specification):
         "w",
     ) as file:
         file.write(
-            """# AUTO GENERATED ON {0}
+            f"""# AUTO GENERATED ON {reproducible_datetime()}
 # DO NOT EDIT BY HAND!
 #
 # To regenerate file, run
@@ -272,9 +270,7 @@ class ERROR(Structure):
 
 def by_signature(lib):
     out = {{}}
-""".format(
-                reproducible_datetime()
-            )
+"""
         )
 
         for spec in specification["kernels"]:
diff --git a/dev/generate-tests.py b/dev/generate-tests.py
index dc168c99eb..d4df2bcd19 100644
--- a/dev/generate-tests.py
+++ b/dev/generate-tests.py
@@ -234,7 +234,7 @@ def genpykernels():
     os.mkdir(tests_spec)
     with open(os.path.join(tests_spec, "__init__.py"), "w") as f:
         f.write(
-            """# AUTO GENERATED ON {}
+            f"""# AUTO GENERATED ON {reproducible_datetime()}
 # DO NOT EDIT BY HAND!
 #
 # To regenerate file, run
@@ -244,9 +244,7 @@ def genpykernels():
 
 # fmt: off
 
-""".format(
-                reproducible_datetime()
-            )
+"""
         )
 
     with open(
@@ -323,7 +321,7 @@ def genspectests(specdict):
             "w",
         ) as f:
             f.write(
-                """# AUTO GENERATED ON {}
+                f"""# AUTO GENERATED ON {reproducible_datetime()}
 # DO NOT EDIT BY HAND!
 #
 # To regenerate file, run
@@ -333,9 +331,7 @@ def genspectests(specdict):
 
 # fmt: off
 
-""".format(
-                    reproducible_datetime()
-                )
+"""
             )
             f.write("import pytest\nimport kernels\n\n")
             num = 1
@@ -437,7 +433,7 @@ def gencpukerneltests(specdict):
     os.mkdir(tests_cpu_kernels)
     with open(os.path.join(tests_cpu_kernels, "__init__.py"), "w") as f:
         f.write(
-            """# AUTO GENERATED ON {}
+            f"""# AUTO GENERATED ON {reproducible_datetime()}
 # DO NOT EDIT BY HAND!
 #
 # To regenerate file, run
@@ -447,9 +443,7 @@ def gencpukerneltests(specdict):
 
 # fmt: off
 
-""".format(
-                reproducible_datetime()
-            )
+"""
         )
 
     for spec in specdict.values():
@@ -457,7 +451,7 @@ def gencpukerneltests(specdict):
             os.path.join(tests_cpu_kernels, "test_cpu" + spec.name + ".py"), "w"
         ) as f:
             f.write(
-                """# AUTO GENERATED ON {}
+                f"""# AUTO GENERATED ON {reproducible_datetime()}
 # DO NOT EDIT BY HAND!
 #
 # To regenerate file, run
@@ -467,9 +461,7 @@ def gencpukerneltests(specdict):
 
 # fmt: off
 
-""".format(
-                    reproducible_datetime()
-                )
+"""
             )
 
             f.write(
@@ -637,7 +629,7 @@ def gencudakerneltests(specdict):
     os.mkdir(tests_cuda_kernels)
     with open(os.path.join(tests_cuda_kernels, "__init__.py"), "w") as f:
         f.write(
-            """# AUTO GENERATED ON {}
+            f"""# AUTO GENERATED ON {reproducible_datetime()}
 # DO NOT EDIT BY HAND!
 #
 # To regenerate file, run
@@ -647,9 +639,7 @@ def gencudakerneltests(specdict):
 
 # fmt: off
 
-""".format(
-                reproducible_datetime()
-            )
+"""
         )
 
     for spec in specdict.values():
@@ -658,7 +648,7 @@ def gencudakerneltests(specdict):
                 os.path.join(tests_cuda_kernels, "test_cuda" + spec.name + ".py"), "w"
             ) as f:
                 f.write(
-                    """# AUTO GENERATED ON {}
+                    f"""# AUTO GENERATED ON {reproducible_datetime()}
 # DO NOT EDIT BY HAND!
 #
 # To regenerate file, run
@@ -668,9 +658,7 @@ def gencudakerneltests(specdict):
 
 # fmt: off
 
-""".format(
-                        reproducible_datetime()
-                    )
+"""
                 )
 
                 f.write(
diff --git a/src/awkward/_backends/backend.py b/src/awkward/_backends/backend.py
index b7079e8288..9350a1beae 100644
--- a/src/awkward/_backends/backend.py
+++ b/src/awkward/_backends/backend.py
@@ -14,7 +14,7 @@
 numpy = Numpy.instance()
 
 
-T = TypeVar("T", covariant=True)
+T_co = TypeVar("T_co", covariant=True)
 KernelKeyType: TypeAlias = Tuple[str, Unpack[Tuple[np.dtype, ...]]]
 KernelType: TypeAlias = "Callable[..., KernelError | None]"
 
diff --git a/src/awkward/_connect/numba/arrayview.py b/src/awkward/_connect/numba/arrayview.py
index 7311815007..59812ac7c4 100644
--- a/src/awkward/_connect/numba/arrayview.py
+++ b/src/awkward/_connect/numba/arrayview.py
@@ -239,9 +239,7 @@ def repr_behavior(behavior):
 class ArrayViewType(numba.types.IterableType, numba.types.Sized):
     def __init__(self, type, behavior, fields):
         super().__init__(
-            name="ak.ArrayView({}, {}, {})".format(
-                type.name, repr_behavior(behavior), repr(fields)
-            )
+            name=f"ak.ArrayView({type.name}, {repr_behavior(behavior)}, {fields!r})"
         )
         self.type = type
         self.behavior = behavior
diff --git a/src/awkward/_do.py b/src/awkward/_do.py
index 54f7e0c9f0..aa4b645fa4 100644
--- a/src/awkward/_do.py
+++ b/src/awkward/_do.py
@@ -172,9 +172,7 @@ def unique(layout: Content, axis=None):
                     negaxis = negaxis + depth
                 if not (0 < negaxis and negaxis <= depth):
                     raise AxisError(
-                        "axis={} exceeds the depth of this array ({})".format(
-                            axis, depth
-                        )
+                        f"axis={axis} exceeds the depth of this array ({depth})"
                     )
 
         starts = ak.index.Index64.zeros(1, nplike=layout._backend.index_nplike)
@@ -185,9 +183,7 @@ def unique(layout: Content, axis=None):
         return layout._unique(negaxis, starts, parents, 1)
 
     raise AxisError(
-        "unique expects axis 'None' or '-1', got axis={} that is not supported yet".format(
-            axis
-        )
+        f"unique expects axis 'None' or '-1', got axis={axis} that is not supported yet"
     )
 
 
diff --git a/src/awkward/contents/content.py b/src/awkward/contents/content.py
index de558fe176..e6211f3e6c 100644
--- a/src/awkward/contents/content.py
+++ b/src/awkward/contents/content.py
@@ -218,9 +218,7 @@ def getkey(layout):
 
         else:
             raise TypeError(
-                "form_key must be None, a string, or a callable, not {}".format(
-                    type(form_key)
-                )
+                f"form_key must be None, a string, or a callable, not {type(form_key)}"
             )
 
         return self._form_with_key(getkey)
@@ -268,11 +266,7 @@ def _repr_extra(self, indent: str) -> list[str]:
         out = []
         if self._parameters is not None:
             for k, v in self._parameters.items():
-                out.append(
-                    "\n{}<parameter name={}>{}</parameter>".format(
-                        indent, repr(k), repr(v)
-                    )
-                )
+                out.append(f"\n{indent}<parameter name={k!r}>{v!r}</parameter>")
         return out
 
     def maybe_to_NumpyArray(self):
diff --git a/src/awkward/contents/indexedarray.py b/src/awkward/contents/indexedarray.py
index 4918a0c838..e1a47c4840 100644
--- a/src/awkward/contents/indexedarray.py
+++ b/src/awkward/contents/indexedarray.py
@@ -965,9 +965,7 @@ def _validity_error(self, path):
                     errors="surrogateescape"
                 ).lstrip("\n").lstrip("(")
             message = error.str.decode(errors="surrogateescape")
-            return 'at {} ("{}"): {} at i={}{}'.format(
-                path, type(self), message, error.id, filename
-            )
+            return f'at {path} ("{type(self)}"): {message} at i={error.id}{filename}'
 
         else:
             return self._content._validity_error(path + ".content")
diff --git a/src/awkward/contents/indexedoptionarray.py b/src/awkward/contents/indexedoptionarray.py
index 5b7e7b3df3..b1a0783001 100644
--- a/src/awkward/contents/indexedoptionarray.py
+++ b/src/awkward/contents/indexedoptionarray.py
@@ -1480,9 +1480,7 @@ def _validity_error(self, path):
                     errors="surrogateescape"
                 ).lstrip("\n").lstrip("(")
             message = error.str.decode(errors="surrogateescape")
-            return 'at {} ("{}"): {} at i={}{}'.format(
-                path, type(self), message, error.id, filename
-            )
+            return f'at {path} ("{type(self)}"): {message} at i={error.id}{filename}'
 
         else:
             return self._content._validity_error(path + ".content")
diff --git a/src/awkward/contents/listarray.py b/src/awkward/contents/listarray.py
index 595f463730..814112a8fa 100644
--- a/src/awkward/contents/listarray.py
+++ b/src/awkward/contents/listarray.py
@@ -1357,9 +1357,7 @@ def _validity_error(self, path):
                     errors="surrogateescape"
                 ).lstrip("\n").lstrip("(")
             message = error.str.decode(errors="surrogateescape")
-            return 'at {} ("{}"): {} at i={}{}'.format(
-                path, type(self), message, error.id, filename
-            )
+            return f'at {path} ("{type(self)}"): {message} at i={error.id}{filename}'
         else:
             return self._content._validity_error(path + ".content")
 
diff --git a/src/awkward/contents/listoffsetarray.py b/src/awkward/contents/listoffsetarray.py
index 4a2ab99358..cdaf7ab9a4 100644
--- a/src/awkward/contents/listoffsetarray.py
+++ b/src/awkward/contents/listoffsetarray.py
@@ -116,9 +116,7 @@ def __init__(self, offsets, content, *, parameters=None):
             )
         if offsets.length is not unknown_length and offsets.length == 0:
             raise ValueError(
-                "{} len(offsets) ({}) must be >= 1".format(
-                    type(self).__name__, offsets.length
-                )
+                f"{type(self).__name__} len(offsets) ({offsets.length}) must be >= 1"
             )
 
         if parameters is not None and parameters.get("__array__") == "string":
@@ -1758,9 +1756,7 @@ def _validity_error(self, path):
                     errors="surrogateescape"
                 ).lstrip("\n").lstrip("(")
             message = error.str.decode(errors="surrogateescape")
-            return 'at {} ("{}"): {} at i={}{}'.format(
-                path, type(self), message, error.id, filename
-            )
+            return f'at {path} ("{type(self)}"): {message} at i={error.id}{filename}'
         else:
             return self._content._validity_error(path + ".content")
 
diff --git a/src/awkward/contents/unionarray.py b/src/awkward/contents/unionarray.py
index a8add73bd1..e8237d1c2d 100644
--- a/src/awkward/contents/unionarray.py
+++ b/src/awkward/contents/unionarray.py
@@ -1400,9 +1400,7 @@ def _validity_error(self, path):
                     errors="surrogateescape"
                 ).lstrip("\n").lstrip("(")
             message = error.str.decode(errors="surrogateescape")
-            return 'at {} ("{}"): {} at i={}{}'.format(
-                path, type(self), message, error.id, filename
-            )
+            return f'at {path} ("{type(self)}"): {message} at i={error.id}{filename}'
 
         # Check triangular pairs (i, j) are not mergeable
         for i, content_i in enumerate(self._contents):
diff --git a/src/awkward/forms/bitmaskedform.py b/src/awkward/forms/bitmaskedform.py
index 72ac02b372..9c2ed21875 100644
--- a/src/awkward/forms/bitmaskedform.py
+++ b/src/awkward/forms/bitmaskedform.py
@@ -22,9 +22,7 @@ def __init__(
     ):
         if not isinstance(mask, str):
             raise TypeError(
-                "{} 'mask' must be of type str, not {}".format(
-                    type(self).__name__, repr(mask)
-                )
+                f"{type(self).__name__} 'mask' must be of type str, not {mask!r}"
             )
         if not isinstance(content, Form):
             raise TypeError(
@@ -40,9 +38,7 @@ def __init__(
             )
         if not isinstance(lsb_order, bool):
             raise TypeError(
-                "{} 'lsb_order' must be bool, not {}".format(
-                    type(self).__name__, repr(lsb_order)
-                )
+                f"{type(self).__name__} 'lsb_order' must be bool, not {lsb_order!r}"
             )
 
         self._mask = mask
diff --git a/src/awkward/forms/bytemaskedform.py b/src/awkward/forms/bytemaskedform.py
index 511c04762f..28a7f25f49 100644
--- a/src/awkward/forms/bytemaskedform.py
+++ b/src/awkward/forms/bytemaskedform.py
@@ -21,9 +21,7 @@ def __init__(
     ):
         if not isinstance(mask, str):
             raise TypeError(
-                "{} 'mask' must be of type str, not {}".format(
-                    type(self).__name__, repr(mask)
-                )
+                f"{type(self).__name__} 'mask' must be of type str, not {mask!r}"
             )
         if not isinstance(content, Form):
             raise TypeError(
diff --git a/src/awkward/forms/indexedform.py b/src/awkward/forms/indexedform.py
index a972606a81..4903dbb5f7 100644
--- a/src/awkward/forms/indexedform.py
+++ b/src/awkward/forms/indexedform.py
@@ -21,9 +21,7 @@ def __init__(
     ):
         if not isinstance(index, str):
             raise TypeError(
-                "{} 'index' must be of type str, not {}".format(
-                    type(self).__name__, repr(index)
-                )
+                f"{type(self).__name__} 'index' must be of type str, not {index!r}"
             )
         if not isinstance(content, Form):
             raise TypeError(
diff --git a/src/awkward/forms/indexedoptionform.py b/src/awkward/forms/indexedoptionform.py
index dc68beb139..80a791c78e 100644
--- a/src/awkward/forms/indexedoptionform.py
+++ b/src/awkward/forms/indexedoptionform.py
@@ -21,9 +21,7 @@ def __init__(
     ):
         if not isinstance(index, str):
             raise TypeError(
-                "{} 'index' must be of type str, not {}".format(
-                    type(self).__name__, repr(index)
-                )
+                f"{type(self).__name__} 'index' must be of type str, not {index!r}"
             )
         if not isinstance(content, Form):
             raise TypeError(
diff --git a/src/awkward/forms/recordform.py b/src/awkward/forms/recordform.py
index 7032a45f0e..0878464bb2 100644
--- a/src/awkward/forms/recordform.py
+++ b/src/awkward/forms/recordform.py
@@ -37,9 +37,7 @@ def __init__(
                 )
         if fields is not None and not isinstance(fields, Iterable):
             raise TypeError(
-                "{} 'fields' must be iterable, not {}".format(
-                    type(self).__name__, repr(contents)
-                )
+                f"{type(self).__name__} 'fields' must be iterable, not {contents!r}"
             )
 
         self._fields = None if fields is None else list(fields)
@@ -99,9 +97,7 @@ def index_to_field(self, index):
                 return self._fields[index]
         else:
             raise IndexError(
-                "no index {} in record with {} fields".format(
-                    index, len(self._contents)
-                )
+                f"no index {index} in record with {len(self._contents)} fields"
             )
 
     def field_to_index(self, field):
@@ -121,9 +117,7 @@ def field_to_index(self, field):
             else:
                 return i
         raise FieldNotFoundError(
-            "no field {} in record with {} fields".format(
-                repr(field), len(self._contents)
-            )
+            f"no field {field!r} in record with {len(self._contents)} fields"
         )
 
     def has_field(self, field):
diff --git a/src/awkward/forms/unionform.py b/src/awkward/forms/unionform.py
index 5a1f35c42d..3d7e080b53 100644
--- a/src/awkward/forms/unionform.py
+++ b/src/awkward/forms/unionform.py
@@ -24,15 +24,11 @@ def __init__(
     ):
         if not isinstance(tags, str):
             raise TypeError(
-                "{} 'tags' must be of type str, not {}".format(
-                    type(self).__name__, repr(tags)
-                )
+                f"{type(self).__name__} 'tags' must be of type str, not {tags!r}"
             )
         if not isinstance(index, str):
             raise TypeError(
-                "{} 'index' must be of type str, not {}".format(
-                    type(self).__name__, repr(index)
-                )
+                f"{type(self).__name__} 'index' must be of type str, not {index!r}"
             )
         if not isinstance(contents, Iterable):
             raise TypeError(
diff --git a/src/awkward/operations/ak_from_parquet.py b/src/awkward/operations/ak_from_parquet.py
index 23755951b2..298d8576ca 100644
--- a/src/awkward/operations/ak_from_parquet.py
+++ b/src/awkward/operations/ak_from_parquet.py
@@ -166,7 +166,7 @@ def metadata(
         actual_paths = []
         for select in row_groups:
             path = rgs_path[select]
-            path2 = [_ for _ in all_paths if _.endswith(path)][0]
+            path2 = next(_ for _ in all_paths if _.endswith(path))
             if path2 not in actual_paths:
                 actual_paths.append(path2)
                 subrg.append([path_rgs[path].index(select)])
diff --git a/src/awkward/types/recordtype.py b/src/awkward/types/recordtype.py
index df42e827ed..c2abe46875 100644
--- a/src/awkward/types/recordtype.py
+++ b/src/awkward/types/recordtype.py
@@ -50,9 +50,7 @@ def __init__(self, contents, fields, *, parameters=None, typestr=None):
                 )
         if fields is not None and not isinstance(fields, Iterable):
             raise TypeError(
-                "{} 'fields' must be iterable, not {}".format(
-                    type(self).__name__, repr(contents)
-                )
+                f"{type(self).__name__} 'fields' must be iterable, not {contents!r}"
             )
         if parameters is not None and not isinstance(parameters, dict):
             raise TypeError(
diff --git a/tests/test_0014_finish_up_getitem.py b/tests/test_0014_finish_up_getitem.py
index 07a52e674b..1107a2f4c3 100644
--- a/tests/test_0014_finish_up_getitem.py
+++ b/tests/test_0014_finish_up_getitem.py
@@ -105,7 +105,6 @@ def test_listoffsetarrayA64():
         for cuts in itertools.permutations(
             ([2, 0, 0, 1], [1, -2, 0, -1], slice(1, None), slice(None, -1)), depth
         ):
-            cuts = cuts
             while len(cuts) > 0 and isinstance(cuts[0], slice):
                 cuts = cuts[1:]
             while len(cuts) > 0 and isinstance(cuts[-1], slice):
@@ -167,7 +166,6 @@ def test_listoffsetarrayA32():
         for cuts in itertools.permutations(
             ([2, 0, 0, 1], [1, -2, 0, -1], slice(1, None), slice(None, -1)), depth
         ):
-            cuts = cuts
             while len(cuts) > 0 and isinstance(cuts[0], slice):
                 cuts = cuts[1:]
             while len(cuts) > 0 and isinstance(cuts[-1], slice):
@@ -225,7 +223,6 @@ def test_listarrayA64():
         for cuts in itertools.permutations(
             ([2, 0, 0, 1], [1, -2, 0, -1], slice(1, None), slice(None, -1)), depth
         ):
-            cuts = cuts
             while len(cuts) > 0 and isinstance(cuts[0], slice):
                 cuts = cuts[1:]
             while len(cuts) > 0 and isinstance(cuts[-1], slice):
@@ -282,7 +279,6 @@ def test_listarrayA32():
         for cuts in itertools.permutations(
             ([2, 0, 0, 1], [1, -2, 0, -1], slice(1, None), slice(None, -1)), depth
         ):
-            cuts = cuts
             while len(cuts) > 0 and isinstance(cuts[0], slice):
                 cuts = cuts[1:]
             while len(cuts) > 0 and isinstance(cuts[-1], slice):
@@ -321,7 +317,6 @@ def test_listoffsetarrayB64():
         for cuts in itertools.permutations(
             (-1, 0, [1, 0, 0, 1], [0, 1, -1, 1], slice(None, -1)), depth
         ):
-            cuts = cuts
             while len(cuts) > 0 and isinstance(cuts[0], slice):
                 cuts = cuts[1:]
             while len(cuts) > 0 and isinstance(cuts[-1], slice):
@@ -361,7 +356,6 @@ def test_listoffsetarrayB32():
         for cuts in itertools.permutations(
             (-1, 0, [1, 0, 0, 1], [0, 1, -1, 1], slice(None, -1)), depth
         ):
-            cuts = cuts
             while len(cuts) > 0 and isinstance(cuts[0], slice):
                 cuts = cuts[1:]
             while len(cuts) > 0 and isinstance(cuts[-1], slice):
@@ -399,7 +393,6 @@ def test_listarrayB64():
         for cuts in itertools.permutations(
             (-1, 0, [1, 0, 0, 1], [0, 1, -1, 1], slice(None, -1)), depth
         ):
-            cuts = cuts
             while len(cuts) > 0 and isinstance(cuts[0], slice):
                 cuts = cuts[1:]
             while len(cuts) > 0 and isinstance(cuts[-1], slice):
@@ -436,7 +429,6 @@ def test_listarrayB32():
         for cuts in itertools.permutations(
             (-1, 0, [1, 0, 0, 1], [0, 1, -1, 1], slice(None, -1)), depth
         ):
-            cuts = cuts
             while len(cuts) > 0 and isinstance(cuts[0], slice):
                 cuts = cuts[1:]
             while len(cuts) > 0 and isinstance(cuts[-1], slice):
diff --git a/tests/test_0023_regular_array.py b/tests/test_0023_regular_array.py
index 1a6e19647e..4ec8d31e42 100644
--- a/tests/test_0023_regular_array.py
+++ b/tests/test_0023_regular_array.py
@@ -193,7 +193,6 @@ def test_numpy():
         for cuts in itertools.permutations(
             ([2, 0, 0, 1], [1, -2, 0, -1], slice(1, None), slice(None, -1)), depth
         ):
-            cuts = cuts
             while len(cuts) > 0 and isinstance(cuts[0], slice):
                 cuts = cuts[1:]
             while len(cuts) > 0 and isinstance(cuts[-1], slice):
@@ -228,7 +227,6 @@ def test_numpy():
         for cuts in itertools.permutations(
             (-1, 0, [1, 0, 0, 1], [0, 1, -1, 1], slice(None, -1)), depth
         ):
-            cuts = cuts
             while len(cuts) > 0 and isinstance(cuts[0], slice):
                 cuts = cuts[1:]
             while len(cuts) > 0 and isinstance(cuts[-1], slice):