Issue Summary

When Jira is configured to use 4‑digit year formats for all date settings (Advanced Settings and Look & Feel), Date Picker fields still accept manually entered 2‑digit years. The value is then interpreted as a literal year 00xx and displayed as such (e.g. 13/Feb/26 → 13/Feb/0026). This contradicts the configured yyyy pattern and can silently introduce invalid historical dates into issues and custom fields.

This is distinct from JRASERVER‑31291 (which changed default formats from yy to yyyy and fixed the 2044→1944 class of issues). Here, even with yyyy configured everywhere, the parser still accepts 2‑digit year input and stores it as a year in the 00xx range.

Steps to Reproduce

1. Preconditions (configuration)

1. 1. In Administration → System → General configuration → Advanced settings, set:

• • • jira.date.picker.java.format = d/MMM/yyyy

• • • jira.date.picker.javascript.format = %e/%b/%Y

• • • jira.date.time.picker.java.format = dd/MMM/yyyy h:mm a

• • • jira.date.time.picker.javascript.format = %e/%b/%Y %I:%M %p

1. 1. In Administration → System → User Interface → Look and feel → Date / time formats, set:

• • • Complete Date/Time Format: dd/MMM/yyyy h:mm a

• • • Day/Month/Year Format: dd/MMM/yyyy

Repro steps

1. 1. Go to Administration → Issues → Custom fields.

1. 1. Create a new custom field of type Date Picker, e.g. name it Repro Date Picker.

1. 1. Add this field to a Create screen for any test project.

1. 1. Open the Create Issue screen for that project.

1. 1. Locate the Repro Date Picker field, click into it, and manually type:
      13/Feb/26
      (matches d/MMM/yyyy except the year has only 2 digits).

1. 1. Submit the form to create the issue.

1. 1. View the created issue and observe the value of the Repro Date Picker field.
      

Expected Results

• With all system date formats configured to a 4‑digit year (yyyy / %Y):

• • Jira should either:

• • • Reject 2‑digit year input (e.g. 13/Feb/26) as invalid for a yyyy pattern, or

• • • Normalize it to an appropriate 4‑digit year (e.g. interpret 26 as 2026 based on a documented rule).

• Under no circumstance should Jira silently interpret 26 as the year 0026 when the configured pattern explicitly requires 4 digits.

Actual Results

• The Create Issue operation succeeds; no validation error is shown for the Date Picker field.

• On the issue view, the Repro Date Picker field displays:
  13/Feb/0026

• I.e. Jira interprets the manually entered 2‑digit year 26 as the literal year 0026, despite the system‑wide yyyy configuration.

This behavior also affects Date Time Picker fields when a 2‑digit year is manually entered (e.g. 13/Feb/26 3:55 PM → 13/Feb/0026 3:55 PM).

Workaround

There is no configuration‑only workaround to make Jira strictly reject or normalize 2‑digit year input when using yyyy / %Y.