diff --git a/dvc/config_schema.py b/dvc/config_schema.py
--- a/dvc/config_schema.py
+++ b/dvc/config_schema.py
@@ -51,6 +51,8 @@ def validate(data):
         # Windows absolute paths should really have scheme == "" (local)
         if os.name == "nt" and len(parsed.scheme) == 1 and parsed.netloc == "":
             return schemas[""](data)
+        if parsed.netloc == "":
+            return schemas[""](data)
         if parsed.scheme not in schemas:
             raise Invalid(f"Unsupported URL type {parsed.scheme}://")
 

I can reproduce it. it's a bug of `dvc add`
related: https://github.com/iterative/dvc-objects/issues/177
It is happening because we consider the filename also a URL. And urlparse returns filena as scheme.
This should be resolved by https://github.com/iterative/dvc-objects/pull/179
> This should be resolved by https://github.com/iterative/dvc-objects/pull/179

@pmrowla This one is different and not resolved by the link. It fails at config validation:

https://github.com/iterative/dvc/blob/f68a12558aac7da25c721877e855d5c115d07261/dvc/config_schema.py#L50-L55






I can reproduce it. it's a bug of `dvc add`
related: https://github.com/iterative/dvc-objects/issues/177
It is happening because we consider the filename also a URL. And urlparse returns filena as scheme.
This should be resolved by https://github.com/iterative/dvc-objects/pull/179
> This should be resolved by https://github.com/iterative/dvc-objects/pull/179

@pmrowla This one is different and not resolved by the link. It fails at config validation:

https://github.com/iterative/dvc/blob/f68a12558aac7da25c721877e855d5c115d07261/dvc/config_schema.py#L50-L55






diff --git a/tests/func/test_add.py b/tests/func/test_add.py
--- a/tests/func/test_add.py
+++ b/tests/func/test_add.py
@@ -342,6 +342,13 @@ def test_double_add_unchanged_dir(tmp_dir, dvc):
     assert ret == 0
 
 
+@pytest.mark.skipif(os.name == "nt", reason="unsupported on Windows")
+def test_add_colon_in_filename(tmp_dir, dvc):
+    tmp_dir.gen("fo:o", "foo")
+    ret = main(["add", "fo:o"])
+    assert ret == 0
+
+
 def test_should_update_state_entry_for_file_after_add(mocker, dvc, tmp_dir):
     file_md5_counter = mocker.spy(dvc_data.hashfile.hash, "file_md5")
     tmp_dir.gen("foo", "foo")

add: Filenames containing the : character give an error.
# Bug Report

<!--
## Issue name

Issue names must follow the pattern `command: description` where the command is the dvc command that you are trying to run. The description should describe the consequence of the bug.

Example: `repro: doesn't detect input changes`
-->

## Description

<!--
A clear and concise description of what the bug is.
-->

DVC doesn't recognise file paths containing the : character, and instead tries to treat them as URLs, giving the error (for the file filena:me):

```console
ERROR: config file error: Unsupported URL type filena:// 
```

### Reproduce

<!--
Step list of how to reproduce the bug
-->

<!--
Example:

1. dvc init
2. Copy dataset.zip to the directory
3. dvc add dataset.zip
4. dvc run -d dataset.zip -o model ./train.sh
5. modify dataset.zip
6. dvc repro
-->
1. dvc init
2. touch filena:me
3. dvc add filena:me
### Expected

<!--
A clear and concise description of what you expect to happen.
-->
File should be added to the dvc repository.
### Environment information

<!--
This is required to ensure that we can reproduce the bug.
-->

**Output of `dvc doctor`:**

```console
DVC version: 2.38.1 (conda)
---------------------------------
Platform: Python 3.11.0 on macOS-13.1-arm64-arm-64bit
Subprojects:
	dvc_data = 0.28.4
	dvc_objects = 0.14.0
	dvc_render = 0.0.15
	dvc_task = 0.1.8
	dvclive = 1.3.0
	scmrepo = 0.1.4
Supports:
	http (aiohttp = 3.8.3, aiohttp-retry = 2.8.3),
	https (aiohttp = 3.8.3, aiohttp-retry = 2.8.3),
	ssh (sshfs = 2022.6.0)
Cache types: <https://error.dvc.org/no-dvc-cache>
Caches: local
Remotes: None
Workspace directory: apfs on /dev/disk3s1s1
Repo: dvc, git
```

**Additional Information (if any):**

<!--
Please check https://github.com/iterative/dvc/wiki/Debugging-DVC on ways to gather more information regarding the issue.

If applicable, please also provide a `--verbose` output of the command, eg: `dvc add --verbose`.
If the issue is regarding the performance, please attach the profiling information and the benchmark comparisons.
-->

add: Filenames containing the : character give an error.
# Bug Report

<!--
## Issue name

Issue names must follow the pattern `command: description` where the command is the dvc command that you are trying to run. The description should describe the consequence of the bug.

Example: `repro: doesn't detect input changes`
-->

## Description

<!--
A clear and concise description of what the bug is.
-->

DVC doesn't recognise file paths containing the : character, and instead tries to treat them as URLs, giving the error (for the file filena:me):

```console
ERROR: config file error: Unsupported URL type filena:// 
```

### Reproduce

<!--
Step list of how to reproduce the bug
-->

<!--
Example:

1. dvc init
2. Copy dataset.zip to the directory
3. dvc add dataset.zip
4. dvc run -d dataset.zip -o model ./train.sh
5. modify dataset.zip
6. dvc repro
-->
1. dvc init
2. touch filena:me
3. dvc add filena:me
### Expected

<!--
A clear and concise description of what you expect to happen.
-->
File should be added to the dvc repository.
### Environment information

<!--
This is required to ensure that we can reproduce the bug.
-->

**Output of `dvc doctor`:**

```console
DVC version: 2.38.1 (conda)
---------------------------------
Platform: Python 3.11.0 on macOS-13.1-arm64-arm-64bit
Subprojects:
	dvc_data = 0.28.4
	dvc_objects = 0.14.0
	dvc_render = 0.0.15
	dvc_task = 0.1.8
	dvclive = 1.3.0
	scmrepo = 0.1.4
Supports:
	http (aiohttp = 3.8.3, aiohttp-retry = 2.8.3),
	https (aiohttp = 3.8.3, aiohttp-retry = 2.8.3),
	ssh (sshfs = 2022.6.0)
Cache types: <https://error.dvc.org/no-dvc-cache>
Caches: local
Remotes: None
Workspace directory: apfs on /dev/disk3s1s1
Repo: dvc, git
```

**Additional Information (if any):**

<!--
Please check https://github.com/iterative/dvc/wiki/Debugging-DVC on ways to gather more information regarding the issue.

If applicable, please also provide a `--verbose` output of the command, eg: `dvc add --verbose`.
If the issue is regarding the performance, please attach the profiling information and the benchmark comparisons.
-->


tests/func/test_add.py::test_add_colon_in_filename
tests/func/test_add.py::test_add tests/func/test_add.py::test_add_executable tests/func/test_add.py::test_add_unicode tests/func/test_add.py::test_add_unsupported_file tests/func/test_add.py::test_add_directory tests/func/test_add.py::test_add_directory_recursive tests/func/test_add.py::test_add_cmd_directory_recursive tests/func/test_add.py::test_warn_about_large_directories_recursive_add tests/func/test_add.py::test_add_directory_with_forward_slash tests/func/test_add.py::test_add_tracked_file tests/func/test_add.py::test_add_dir_with_existing_cache tests/func/test_add.py::test_add_modified_dir tests/func/test_add.py::test_add_file_in_dir tests/func/test_add.py::test_add_filtered_files_in_dir[dir/subdir/subdata*-expected_def_paths0-expected_rel_paths0] tests/func/test_add.py::test_add_filtered_files_in_dir[dir/subdir/?subdata-expected_def_paths1-expected_rel_paths1] tests/func/test_add.py::test_add_filtered_files_in_dir[dir/subdir/[aiou]subdata-expected_def_paths2-expected_rel_paths2] tests/func/test_add.py::test_add_filtered_files_in_dir[dir/**/subdata*-expected_def_paths3-expected_rel_paths3] tests/func/test_add.py::TestAddExternal::test_add tests/func/test_add.py::TestAddExternal::test_add_dir tests/func/test_add.py::test_add_external_relpath tests/func/test_add.py::test_add_local_remote_file tests/func/test_add.py::test_cmd_add tests/func/test_add.py::test_double_add_unchanged_file tests/func/test_add.py::test_double_add_unchanged_dir tests/func/test_add.py::test_should_update_state_entry_for_file_after_add tests/func/test_add.py::test_should_update_state_entry_for_directory_after_add tests/func/test_add.py::test_add_commit tests/func/test_add.py::test_should_collect_dir_cache_only_once tests/func/test_add.py::test_should_place_stage_in_data_dir_if_repository_below_symlink tests/func/test_add.py::test_should_throw_proper_exception_on_corrupted_stage_file tests/func/test_add.py::test_add_filename tests/func/test_add.py::test_failed_add_cleanup tests/func/test_add.py::test_should_not_track_git_internal_files tests/func/test_add.py::test_readding_dir_should_not_unprotect_all tests/func/test_add.py::test_should_not_checkout_when_adding_cached_copy tests/func/test_add.py::test_should_relink_on_repeated_add[hardlink-copy-<lambda>] tests/func/test_add.py::test_should_relink_on_repeated_add[symlink-copy-<lambda>] tests/func/test_add.py::test_should_relink_on_repeated_add[copy-hardlink-is_hardlink] tests/func/test_add.py::test_should_relink_on_repeated_add[copy-symlink-is_symlink] tests/func/test_add.py::test_escape_gitignore_entries tests/func/test_add.py::test_not_raises_on_re_add tests/func/test_add.py::test_add_empty_files[hardlink] tests/func/test_add.py::test_add_empty_files[symlink] tests/func/test_add.py::test_add_empty_files[copy] tests/func/test_add.py::test_add_optimization_for_hardlink_on_empty_files tests/func/test_add.py::test_output_duplication_for_pipeline_tracked tests/func/test_add.py::test_add_pipeline_file tests/func/test_add.py::test_add_symlink_file tests/func/test_add.py::test_add_symlink_dir[True] tests/func/test_add.py::test_add_symlink_dir[False] tests/func/test_add.py::test_add_file_in_symlink_dir[True] tests/func/test_add.py::test_add_file_in_symlink_dir[False] tests/func/test_add.py::test_add_with_cache_link_error tests/func/test_add.py::test_add_preserve_fields tests/func/test_add.py::test_add_long_fname tests/func/test_add.py::test_add_to_remote tests/func/test_add.py::test_add_to_remote_absolute tests/func/test_add.py::test_add_to_remote_invalid_combinations[multiple tests/func/test_add.py::test_add_to_remote_invalid_combinations[--no-commit-kwargs1] tests/func/test_add.py::test_add_to_remote_invalid_combinations[--recursive-kwargs2] tests/func/test_add.py::test_add_to_remote_invalid_combinations[--external-kwargs3] tests/func/test_add.py::test_add_to_cache_dir tests/func/test_add.py::test_add_to_cache_file tests/func/test_add.py::test_add_with_out tests/func/test_add.py::test_add_to_cache_different_name tests/func/test_add.py::test_add_to_cache_not_exists tests/func/test_add.py::test_add_to_cache_invalid_combinations[multiple tests/func/test_add.py::test_add_to_cache_invalid_combinations[--no-commit-kwargs1] tests/func/test_add.py::test_add_to_cache_invalid_combinations[--recursive-kwargs2] tests/func/test_add.py::test_add_to_cache_from_remote tests/func/test_add.py::test_add_ignored tests/func/test_add.py::test_add_on_not_existing_file_should_not_remove_stage_file tests/func/test_add.py::test_add_does_not_remove_stage_file_on_failure[dvc.repo.index.Index.check_graph] tests/func/test_add.py::test_add_does_not_remove_stage_file_on_failure[dvc.stage.Stage.save] tests/func/test_add.py::test_add_does_not_remove_stage_file_on_failure[dvc.stage.Stage.commit] tests/func/test_add.py::test_add_ignore_duplicated_targets tests/func/test_add.py::test_add_with_annotations tests/func/test_add.py::test_add_updates_to_cloud_versioning_dir