I tested by changing the keyborad to Persian-Farsi in Win 7, no issue when using AZERTY keyboard.

Could you install the tool mozregression to narrow down a regression range in FF48, please. See http://mozilla.github.io/mozregression/ for details. Run the command --good=47 then copy here the final pushlog from the repository mozilla-inbound.

Thank you very much for your reply.

My keyboard layout is Persian (standard). There is no AZERTY keyboard. I saw AZERTY keyboard for Arabic language.

Could you provide a mozegession log?

Here is the mozregression log :

Bisection information: app_name: firefox build_date: 2016-03-16 01:34:41.556000 build_file: C:\Users\magfa\.mozilla\mozregression\persist\9e13da748081--mozilla-inbound--firefox-48.0a1.en-US.win64.zip build_type: inbound build_url: https://queue.taskcluster.net/v1/task/NyZzPuIYS5eecEr2qqnCLQ/runs/0/artifacts/public%2Fbuild%2Ffirefox-48.0a1.en-US.win64.zip changeset: 9e13da74808144fec94192029afad28905ba982a pushlog_url: https://hg.mozilla.org/integration/mozilla-inbound/pushloghtml?fromchange=9e13da74808144fec94192029afad28905ba982a&tochange=1d96035b9f320d0139a6d214affaaeb174d90f5d repo_name: mozilla-inbound repo_url: https://hg.mozilla.org/integration/mozilla-inbound task_id: NyZzPuIYS5eecEr2qqnCLQ

Log view: . . . 2016-10-01T11:02:09: DEBUG : using taskcluster route 'gecko.v2.mozilla-inbound.revision.b540b97736ab5e83ac59cdadeeaa52e766522cd5.firefox.win64-opt' 2016-10-01T11:02:10: INFO : 1475307130031 addons.xpi-utils WARN Disabling foreign installed add-on mozilla_cc2@internetdownloadmanager.com in winreg-app-user 2016-10-01T11:04:52: INFO : Narrowed inbound regression window from [b226ad55, 1d96035b] (5 revisions) to [29022393, 1d96035b] (3 revisions) (~1 steps left) 2016-10-01T11:13:03: INFO : Running mozilla-inbound build built on 2016-03-16 05:28:26.562000, revision eb7c36e2 2016-10-01T11:13:05: INFO : Launching c:\users\magfa\appdata\local\temp\tmpfuoeuy\firefox\firefox.exe 2016-10-01T11:13:06: INFO : application_buildid: 20160315214843 2016-10-01T11:13:06: INFO : application_changeset: eb7c36e2ef5d48262bc8566da9ea37623e7d0883 2016-10-01T11:13:06: INFO : application_display_name: Nightly 2016-10-01T11:13:06: INFO : application_id: {ec8030f7-c20a-464f-9b0e-13a3a9e97384} 2016-10-01T11:13:06: INFO : application_name: Firefox 2016-10-01T11:13:06: INFO : application_remotingname: firefox 2016-10-01T11:13:06: INFO : application_repository: https://hg.mozilla.org/integration/mozilla-inbound 2016-10-01T11:13:06: INFO : application_vendor: Mozilla 2016-10-01T11:13:06: INFO : application_version: 48.0a1 2016-10-01T11:13:06: INFO : platform_buildid: 20160315214843 2016-10-01T11:13:06: INFO : platform_changeset: eb7c36e2ef5d48262bc8566da9ea37623e7d0883 2016-10-01T11:13:06: INFO : platform_repository: https://hg.mozilla.org/integration/mozilla-inbound 2016-10-01T11:13:06: INFO : platform_version: 48.0a1 2016-10-01T11:13:09: INFO : 1475307789228 addons.xpi-utils WARN Disabling foreign installed add-on mozilla_cc2@internetdownloadmanager.com in winreg-app-user 2016-10-01T11:13:33: INFO : Narrowed inbound regression window from [29022393, 1d96035b] (3 revisions) to [29022393, eb7c36e2] (2 revisions) (~1 steps left) 2016-10-01T11:13:33: DEBUG : Starting merge handling... 2016-10-01T11:13:33: DEBUG : Using url: https://hg.mozilla.org/integration/mozilla-inbound/json-pushes?changeset=eb7c36e2ef5d48262bc8566da9ea37623e7d0883&full=1 2016-10-01T11:13:35: DEBUG : Found commit message: Bug 1137563 part.5 Set charCode of dead key's keypress event on Mac to the dead char r=m_kato

2016-10-01T11:13:35: INFO : The bisection is done. 2016-10-01T11:13:35: INFO : Stopped

A bug report has been opened: https://bugzilla.mozilla.org/show_bug.cgi?id=1306868

Feel free to create an account at Bugzilla, maybe a Mozilla dev will contact you to get more info about this regression in Firefox 49.

I installed version 50.0b3 today. This problem is solved. Thank you.