# Analyze Update Verify Logs¶

## When?¶

When update verify tasks fail it is your responsibility as releaseduty to analyze them and determine whether or not any action needs to be taken for any differences found.

## How?¶

Update verify tasks that have failed usually have a diff-summary.log in their artifacts. This file shows you all of the differences found for each update tested. In the diffs, source is an older version Firefox that a MAR file from the current release has been applied to, and target is the full installer for the current release.

Here’s an example of a very alarming difference:

Found diffs for complete update from https://aus5.mozilla.org/update/3/Firefox/59.0/20180215111455/WINNT_x86-msvc/en-US/beta-localtest/default/default/default/update.xml?force=1

Files source/bin/xul.dll and target/bin/xul.dll differ


In the above log, xul.dll is shown to be different between an applied MAR and a full installer. If we were to ship a release with a difference like this, partial MARs would fail to apply for many users in the next release. Usually a case like this represents an issue in the build system or release automation, and requires a rebuild. If you’re not sure how to proceed, ask for help.

If no diff-summary.log is attached to the Task something more serious went wrong. You will need to have a look at live.log to investigate.

## Known differences¶

There are no known cases where diffs are expected, so all task failures should be checked carefully.

See bug 1461490 for the implementation of transforms to resolve expected differences.