spring-projects/spring-boot · error · IllegalArgumentException

Can't parse ' ' to instant

Error message

Can't parse '%s' to instant

What it means

IllegalArgumentException thrown by MavenBuildOutputTimestamp when the non-numeric, non-empty, ≥2-char outputTimestamp cannot be parsed as an OffsetDateTime (DateTimeParseException). The plugin only accepts two formats: pure epoch seconds (numeric) or a valid ISO-8601 offset date-time; anything else lands here.

Solutions

1. Use the ISO-8601 offset form: <outputTimestamp>2024-01-01T00:00:00Z</outputTimestamp>.
2. Or use epoch seconds: <outputTimestamp>1700000000</outputTimestamp> (numeric branch, no parse).
3. Omit the property to disable reproducible-timestamp injection.
4. Validate the value with `OffsetDateTime.parse(...)` in a quick test.

Example fix

// before: <project.build.outputTimestamp>2024/01/01 12:00</project.build.outputTimestamp>
// after:  <project.build.outputTimestamp>2024-01-01T12:00:00Z</project.build.outputTimestamp>

// Validate format before invoking:
String ts = outputTimestamp;
boolean ok = (ts == null || ts.isEmpty())
    || (ts.chars().allMatch(Character::isDigit))
    || canParseOffsetDateTime(ts);
// where:
boolean canParseOffsetDateTime(String s) { try { OffsetDateTime.parse(s); return true; } catch (DateTimeParseException e) { return false; } }

try {
    // invoke goal that calls toFileTime
} catch (IllegalArgumentException ex) {
    if (ex.getMessage().startsWith("Can't parse") && ex.getMessage().endsWith("to instant")) {
        // convert to ISO-8601 offset or epoch seconds, then retry
    }
    throw ex;
}

When it happens

Trigger: Setting <project.build.outputTimestamp> to a non-numeric, non-ISO-8601 string (e.g., '2024/01/01', 'Jan 1 2024', or a date without time/offset that OffsetDateTime.parse rejects).

Common situations: Using a locale-specific date format; passing a LocalDate-only string; missing the offset/zone portion; copy-pasting a timestamp from a non-Java source.

Related errors

• Invalid value for parameter 'outputTimestamp'
• ' ' is not within the valid range to
• A jar or war file is required for building image
• Could not build classpath
• Error packaging archive for image

AI-assisted analysis of spring-projects/spring-boot@270dfe353f (2026-08-11). Data as JSON: /api/errors/c7a770d1da99d778. Report an issue: GitHub.

Appendix: source

Thrown at build-plugin/spring-boot-maven-plugin/src/main/java/org/springframework/boot/maven/MavenBuildOutputTimestamp.java:98

		if (!StringUtils.hasLength(this.timestamp)) {
			return null;
		}
		if (isNumeric(this.timestamp)) {
			return Instant.ofEpochSecond(Long.parseLong(this.timestamp));
		}
		if (this.timestamp.length() < 2) {
			return null;
		}
		try {
			Instant instant = OffsetDateTime.parse(this.timestamp).withOffsetSameInstant(ZoneOffset.UTC).toInstant();
			if (instant.isBefore(DATE_MIN) || instant.isAfter(DATE_MAX)) {
				throw new IllegalArgumentException(
						String.format("'%s' is not within the valid range %s to %s", instant, DATE_MIN, DATE_MAX));
			}
			return instant;
		}
		catch (DateTimeParseException pe) {
			throw new IllegalArgumentException(String.format("Can't parse '%s' to instant", this.timestamp));
		}
	}

	private static boolean isNumeric(String str) {
		for (char c : str.toCharArray()) {
			if (!Character.isDigit(c)) {
				return false;
			}
		}
		return true;
	}

}

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