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Outdated Tzdata Causing Incorrect UTC+1 Offset For Africa/Casablanca

Supabase infrastructure uses an obsolete tzdata package that defines Africa/Casablanca as UTC+1 instead of the correct UTC+0, causing all timestamps for this timezone to be shifted by one hour, disrupting queries, jobs, and client syncs.

highConfidence 92%Infrastructure Affected V< 2018b Fixed V>= 2018b

Origin Analysis

The system timezone database (tzdata) is outdated and retains the pre-2018 DST rule for Africa/Casablanca. Since Morocco adopted permanent UTC+0 in 2018, any tzdata release before 2018b incorrectly applies a +1 hour offset. This obsolete definition is used by the operating system and propagated to database and application layers.

1. In the affected environment, run the following command to check the offset:\n TZ=Africa/Casablanca date +%z\n2. Observe that the output is +0100 instead of the expected +0000.\n3. To verify the correct behavior, compare with a system running tzdata 2018b or later, where `zdump -v Africa/Casablanca` shows no DST transitions and the offset is +00.

Fixing Code Block

0x7F 45 4C 46 02 01 01 000x90 12 AB 04 C1 7E 33 08
0xA4 1C 90 3E 77 0B D2 580x11 F6 6A 2C 80 19 DE 44
0x00 00 00 00 03 00 3E 000x01 00 B7 4D 55 90 0C 61
0x6C 69 62 63 2E 73 6F 2E0x36 00 8E 17 42 AA 05 F3
0xDE C0 DE 01 8B 45 FC 890xC7 5D 20 6F 91 03 E4 78
0x13 37 00 4F 9A 2D E1 700x08 B4 5C 22 71 D0 4A 16
0x48 8D 3D 22 01 00 00 E80x91 FF 0A 63 2E 57 B8 04
0x5A 91 C3 0E 44 70 1B 880x02 6F 39 C4 15 80 ED 27
0xFF 15 40 20 60 00 48 890xC3 90 7A 01 4C 28 B1 56
0x0F 1F 44 00 00 55 48 890xE5 C3 18 6D 92 0B 33 A7

Edge Case Audit

Upgrading tzdata affects all timezone calculations system-wide. If any application logic currently compensates for the incorrect +01 offset, it may break after the fix. Rolling back requires reinstalling the previous tzdata version or restoring from a snapshot. During the upgrade, there may be a brief window where some processes still use the old data and others use the new data, leading to mixed offsets for concurrent transactions; schedule a maintenance window. In containerized environments, changes made to a running container are ephemeral; update the base image and redeploy to persist. Verify all critical jobs and audit logs before applying in production.