FileConfigurationProvider: Handle and forward IO exceptions to OnLoadException by mrek-msft · Pull Request #126093 · dotnet/runtime

mrek-msft · 2026-03-25T15:31:05Z

Current behavior of FileConfigurationProvider on various types of failures at various times:

	First Load	OnChange Reload
data parsing failure	`OnLoadException` callback is called `AddJsonFile` throws	`OnLoadException` callback is called program continues no reload happen
IO failure on file open	`AddJsonFile` throws	Silent program continues no reload happen possibly raises `UnobservedTaskException` later

This PR unifies it in a way that both types of failure behave same as data parsing failure.

This brings some behavioral changes

OnLoadException callback is newly triggered if IO error happen on both types of events (first load, reload)
UnobservedTaskException can no longer be observed in scenario when user registers OnLoadException callback. It can however happen when no callback is registered, so XML comment on OnLoadException was updated.
OnLoadException callbacks now receives not only InvalidDataException, but also IOException (or any other exception which (possibly custom) implementation of IFileProvider can throw). If user cast to InvalidDataException, he may miss other exceptions or get cast exceptions.

Based on follow up Copilot code reviews, I did few more behavior changes at edge cases, they do not relate directly to issue and can be reverted independently if not desired.

OnReload() now fires only when Data actually changed. Previously on first load, if a parse or IO error occurred and OnLoadException set Ignore = true, OnReload() was fired unconditionally even though Data was never modified. The new code fires OnReload() only when Data was successfully loaded or explicitly cleared (e.g., on reload or optional missing file). For consecutive reloads with parse errors, Data is cleared and OnReload() still fires. This change is independent on original fix and can be reverted independently if not desirable.

Fix #113964

Copilot

Pull request overview

Unifies FileConfigurationProvider failure handling so IO failures during file open are handled the same way as parsing failures with respect to OnLoadException (including on reload-on-change), preventing unobserved/unhandled exceptions like the one reported in #113964.

Changes:

Moves stream opening (OpenRead) inside the exception-handling region so IO errors are routed through HandleException/OnLoadException.
Adds an inner try/catch to wrap exceptions thrown by Load(stream) in an InvalidDataException with the standard “Failed to load…” message.
Adjusts the outer catch to forward the exception through HandleException (enabling ignore behavior on reload).

Copilot

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Copilot reviewed 3 out of 3 changed files in this pull request and generated 5 comments.

dotnet-policy-service · 2026-03-26T16:23:35Z

Tagging subscribers to this area: @dotnet/area-extensions-filesystem
See info in area-owners.md if you want to be subscribed.

… file path formatting logic.

Copilot

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated 4 comments.

… forwarding to OnLoadException Agent-Logs-Url: https://github.com/dotnet/runtime/sessions/42d4769b-0756-4ab1-aaae-f73cf4cfaa3d Co-authored-by: mrek-msft <188900745+mrek-msft@users.noreply.github.com>

Copilot

Pull request overview

Copilot reviewed 5 out of 5 changed files in this pull request and generated 2 comments.

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Copilot

Pull request overview

Copilot reviewed 5 out of 5 changed files in this pull request and generated 2 comments.

Copilot

Pull request overview

Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.

tarekgh · 2026-04-21T19:34:24Z

                }
                catch (Exception ex)
                {
                    if (reload)


There is a small behavior change here. Before when the first load fail (reload is false), the OnReload was called. Now it is not. This is fine change with me but would be good if we document it somehow.

tarekgh · 2026-04-21T20:05:09Z

+            catch (Exception ex)
+            {
+                // IO error on file open, preserve existing Data
+                HandleException(ExceptionDispatchInfo.Capture(ex));


Consumers who registered OnLoadException callbacks expecting only FileNotFoundException or InvalidDataException will now receive:

IOException (file locked, disk error)

UnauthorizedAccessException (permission denied)

Any exception from a custom IFileInfo.CreateReadStream()

Maybe it is worth documenting it as a breaking change?

tarekgh

Left minor comments I hope you address them. LGTM, otherwise.

Forward IO exceptions to OnLoadException

cbb97be

Copilot AI review requested due to automatic review settings March 25, 2026 15:31

github-actions Bot added the area-Extensions-Configuration label Mar 25, 2026

dotnet-policy-service Bot assigned mrek-msft Mar 25, 2026

Copilot started reviewing on behalf of mrek-msft March 25, 2026 15:32 View session

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Comment thread ...libraries/Microsoft.Extensions.Configuration.FileExtensions/src/FileConfigurationProvider.cs Outdated

Comment thread ...libraries/Microsoft.Extensions.Configuration.FileExtensions/src/FileConfigurationProvider.cs Outdated

mrek-msft marked this pull request as draft March 25, 2026 15:36

Removed duplicate Data dict recreation

64d03ea

This was referenced Mar 26, 2026

The Operation will be canceled. The next steps may not contain expected logs. dotnet/dnceng#3008

Open

[android-arm64] The Operation will be canceled. The next steps may not contain expected logs. dotnet/dnceng#6408

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Add tests

018c6f6

Copilot AI review requested due to automatic review settings March 26, 2026 16:02

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tarekgh added area-Extensions-FileSystem and removed area-Extensions-Configuration labels Mar 26, 2026

mrek-msft added 4 commits March 26, 2026 17:41

Throw alaways InvalidDataException and clear Data only on data error.

a6e7d92

Improve test attributes assignment.

7e07276

Fix typos

afaa6a4

Change exception back to rpopagating IOException directly and improve…

0a76a86

… file path formatting logic.

Copilot AI review requested due to automatic review settings March 26, 2026 16:59

Copilot started reviewing on behalf of mrek-msft March 26, 2026 17:00 View session

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mrek-msft added 6 commits March 26, 2026 18:10

Fix missing PhysicalPath in error string shown file name selection

4a972f6

Improve comment.

7096d71

Remove duplicate test.

a77d5ca

Add missing ActiveIssue attribute to possibly flaky test.

6f9e61c

Add comment recommended by Copilot

af033ee

Check for type of observed exception.

2ce4531

mrek-msft added 2 commits April 9, 2026 15:43

Fix whitespace formatting

6e934f5

Copilot improved comment

ce0f578

Copilot AI mentioned this pull request Apr 11, 2026

Fix WasmTestOnChrome: exclude browser/wasi from gen-debug-dump-docs.py helix post-command #126789

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rosebyte self-requested a review April 16, 2026 12:15

rosebyte approved these changes Apr 17, 2026

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svick approved these changes Apr 21, 2026

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Comment thread ...libraries/Microsoft.Extensions.Configuration.FileExtensions/src/FileConfigurationProvider.cs Outdated

mrek-msft requested a review from tarekgh April 21, 2026 10:53

Removed old comment

c9d6bca

Copilot AI review requested due to automatic review settings April 21, 2026 11:08

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Comment thread ...libraries/Microsoft.Extensions.Configuration.FileExtensions/src/FileConfigurationProvider.cs

Comment thread ...libraries/Microsoft.Extensions.Configuration.FileExtensions/src/FileConfigurationProvider.cs Outdated

Fix typo in comment

b92542d

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Copilot AI review requested due to automatic review settings April 21, 2026 11:19

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Comment thread src/libraries/Microsoft.Extensions.Configuration/tests/FunctionalTests/ConfigurationTests.cs Outdated

Comment thread src/libraries/Microsoft.Extensions.Configuration/tests/FunctionalTests/ConfigurationTests.cs Outdated

mrek-msft added 3 commits April 21, 2026 14:26

Propagate DirectoryNotFoundException properly.

3bf4ba7

Merge copilot accepted changes to local branch.

db8ae23

Prevent generating UnobservedTaskExceptions in test.

ddae94e

Copilot AI review requested due to automatic review settings April 21, 2026 13:25

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Comment thread ...libraries/Microsoft.Extensions.Configuration.FileExtensions/src/FileConfigurationProvider.cs

This was referenced Apr 21, 2026

Libraries .NET 4.8.1 build failing #127007

Closed

System.DirectoryServices.Protocols.LdapException : The LDAP server is unavailable. #127070

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tarekgh reviewed Apr 21, 2026

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mrek-msft commented Mar 25, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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dotnet-policy-service Bot commented Mar 26, 2026

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mrek-msft commented Mar 25, 2026 •

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