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

mrek-msft · Mar 25, 2026

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

Pull request overview

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

… file path formatting logic.

Copilot

Pull request overview

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

Copilot

Pull request overview

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

tarekgh

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

azure-pipelines · Jul 27, 2026

Azure Pipelines: Successfully started running 3 pipeline(s). 13 pipeline(s) were filtered out due to trigger conditions. There may be pipelines that require an authorized user to comment /azp run to run.

dotnet-policy-service · Jul 27, 2026

Added needs-breaking-change-doc-created label because this PR has the breaking-change label.

When you commit this breaking change:

Create and link to this PR and the issue a matching issue in the dotnet/docs repo using the breaking change documentation template, then remove this needs-breaking-change-doc-created label.
Ask a committer to mail the .NET Breaking Change Notification DL.

Tagging @dotnet/compat for awareness of the breaking change.

mrek-msft · Jul 27, 2026

/backport to release/11.0-preview7

github-actions · Jul 27, 2026

Started backporting to release/11.0-preview7 (link to workflow run)

github-actions · Jul 27, 2026

@mrek-msft backporting to release/11.0-preview7 failed, the patch most likely resulted in conflicts. Please backport manually!

git am output

$ git am --3way --empty=keep --ignore-whitespace --keep-non-patch changes.patch

Applying: Forward IO exceptions to OnLoadException
Applying: Removed duplicate Data dict recreation
Applying: Add tests
Applying: Throw alaways InvalidDataException and clear Data only on data error.
Applying: Improve test attributes assignment.
Applying: Fix typos
Applying: Change exception back to rpopagating IOException directly and improve file path formatting logic.
Applying: Fix missing PhysicalPath in error string shown file name selection
Applying: Improve comment.
Applying: Remove duplicate test.
Applying: Add missing ActiveIssue attribute to possibly flaky test.
Applying: Add comment recommended by Copilot
Applying: Check for type of observed exception.
Applying: Dispose IConfigurationRoot
Applying: Update comment and its location based on Copilot hints
Applying: Do not fire OnReload if no Data change happened.
Applying: Add checking config value after faulty reload
Applying: Move and improve comment.
Applying: Fix double empty line
Applying: Add docs mentioning consequences of not registering OnLoadException.
Applying: Improve test coverage to handle Copilot discovered edge cases
Applying: exclude IOException from handling on "parse error" path.
Applying: Improve comment
Applying: Improve comment
Applying: Fix comment grammar
Applying: Improve FileLoadExceptionContext.Exception comment as requested in PR review
Applying: Removal of nested try..catch and handling deletion explicitly
Applying: Handle file not found in the same way on both paths.
Applying: Fix whitespace formatting
Applying: Copilot improved comment
Applying: Removed old comment
Applying: Fix typo in comment
Applying: Propagate DirectoryNotFoundException properly.
error: sha1 information is lacking or useless (src/libraries/Microsoft.Extensions.Configuration.FileExtensions/src/FileConfigurationProvider.cs).
error: could not build fake ancestor
hint: Use 'git am --show-current-patch=diff' to see the failed patch
hint: When you have resolved this problem, run "git am --continue".
hint: If you prefer to skip this patch, run "git am --skip" instead.
hint: To restore the original branch and stop patching, run "git am --abort".
hint: Disable this message with "git config set advice.mergeConflict false"
Patch failed at 0033 Propagate DirectoryNotFoundException properly.
Error: The process '/usr/bin/git' failed with exit code 128

Link to workflow output

… IO exceptions to OnLoadException (#131427) Backport of #126093 to release/11.0-preview7 ## Customer Impact Long standing issue reported by customer - [X] Customer reported - [ ] Found internally ## Regression Long standing issue. - [ ] Yes - [X] No ## Testing 6 tests were added. ## Risk Low. It is backport to Preview 7 version after branch were snapped but before code complete. Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

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

Copilot AI reviewed Mar 25, 2026

View reviewed changes

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

Closed

Add tests

018c6f6

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

Copilot started reviewing on behalf of mrek-msft March 26, 2026 16:03 View session

Copilot AI reviewed Mar 26, 2026

View reviewed changes

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

Copilot AI reviewed Mar 26, 2026

View reviewed changes

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

Copilot AI review requested due to automatic review settings March 27, 2026 10:48

Prevent generating UnobservedTaskExceptions in test.

ddae94e

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

Copilot started reviewing on behalf of mrek-msft April 21, 2026 13:26 View session

Copilot AI reviewed Apr 21, 2026

View reviewed changes

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

Closed

tarekgh reviewed Apr 21, 2026

View reviewed changes

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

tarekgh reviewed Apr 21, 2026

View reviewed changes

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

tarekgh approved these changes Apr 21, 2026

View reviewed changes

mrek-msft marked this pull request as draft May 14, 2026 12:12

mrek-msft marked this pull request as ready for review July 27, 2026 14:11

mrek-msft added the breaking-change Issue or PR that represents a breaking API or functional change over a previous release. label Jul 27, 2026

dotnet-policy-service Bot added the needs-breaking-change-doc-created Breaking changes need an issue opened with https://github.com/dotnet/docs/issues/new?template=dotnet label Jul 27, 2026

This was referenced Jul 27, 2026

[Breaking change]: FileConfigurationSource.OnLoadException callback is called for IO errors dotnet/docs#55022

Open

[Breaking change]: FileConfigurationProvider.OnReload is not called when Load() fails dotnet/docs#55023

Open

mrek-msft merged commit da60813 into dotnet:main Jul 27, 2026
119 of 122 checks passed

mrek-msft temporarily deployed to copilot-pat-pool July 27, 2026 16:55 — with GitHub Actions Inactive

mrek-msft mentioned this pull request Jul 27, 2026

[release/11.0-preview7] FileConfigurationProvider: Handle and forward IO exceptions to OnLoadException #131427

Merged

4 tasks

mrek-msft removed the needs-breaking-change-doc-created Breaking changes need an issue opened with https://github.com/dotnet/docs/issues/new?template=dotnet label Jul 27, 2026

dotnet-maestro Bot mentioned this pull request Jul 28, 2026

[main] Source code updates from dotnet/runtime dotnet/dotnet#8003

Merged

dotnet-milestone-bot Bot modified the milestones: 11.0.0, 11.0-rc1 Jul 28, 2026

svick mentioned this pull request Jul 28, 2026

Backport workflow should prefer the merged PR change over replaying intermediate commits dotnet/arcade#17205

Open

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mrek-msft commented Mar 25, 2026 •

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