microg/GmsCore · error · IllegalArgumentException

daysSinceOnsetToInfectiousness exceeds MAX_DAYS days

Error message

daysSinceOnsetToInfectiousness exceeds MAX_DAYS days

What it means

DiagnosisKeysDataMappingBuilder.setDaysSinceOnsetToInfectiousness throws IllegalArgumentException when the map contains more than MAX_DAYS entries. The API only supports a bounded window of days since symptom onset, so larger maps cannot be represented.

Source

Thrown at play-services-nearby/src/main/java/com/google/android/gms/nearby/exposurenotification/DiagnosisKeysDataMapping.java:94

        private Integer infectiousnessWhenDaysSinceOnsetMissing;

        public DiagnosisKeysDataMapping build() {
            if (daysSinceOnsetToInfectiousness == null)
                throw new IllegalStateException("Must set daysSinceOnsetToInfectiousness");
            if (reportTypeWhenMissing == ReportType.UNKNOWN)
                throw new IllegalStateException("Must set reportTypeWhenMissing");
            if (infectiousnessWhenDaysSinceOnsetMissing == null)
                throw new IllegalStateException("Must set infectiousnessWhenDaysSinceOnsetMissing");
            DiagnosisKeysDataMapping mapping = new DiagnosisKeysDataMapping();
            mapping.daysSinceOnsetToInfectiousness = new ArrayList<>(daysSinceOnsetToInfectiousness);
            mapping.reportTypeWhenMissing = reportTypeWhenMissing;
            mapping.infectiousnessWhenDaysSinceOnsetMissing = infectiousnessWhenDaysSinceOnsetMissing;
            return mapping;
        }

        public DiagnosisKeysDataMappingBuilder setDaysSinceOnsetToInfectiousness(Map<Integer, Integer> daysSinceOnsetToInfectiousness) {
            if (daysSinceOnsetToInfectiousness.size() > MAX_DAYS)
                throw new IllegalArgumentException("daysSinceOnsetToInfectiousness exceeds " + MAX_DAYS + " days");
            Integer[] values = new Integer[MAX_DAYS];
            Arrays.fill(values, 0);
            for (Map.Entry<Integer, Integer> entry : daysSinceOnsetToInfectiousness.entrySet()) {
                if (entry.getKey() > 14) throw new IllegalArgumentException("invalid day since onset");
                values[entry.getKey() + 14] = entry.getValue();
            }
            this.daysSinceOnsetToInfectiousness = Arrays.asList(values);
            return this;
        }

        public DiagnosisKeysDataMappingBuilder setInfectiousnessWhenDaysSinceOnsetMissing(@Infectiousness int infectiousnessWhenDaysSinceOnsetMissing) {
            this.infectiousnessWhenDaysSinceOnsetMissing = infectiousnessWhenDaysSinceOnsetMissing;
            return this;
        }

        public DiagnosisKeysDataMappingBuilder setReportTypeWhenMissing(@ReportType int reportTypeWhenMissing) {
            this.reportTypeWhenMissing = reportTypeWhenMissing;
            return this;

View on GitHub (pinned to 157c9d86ac)

Solutions

  1. Trim the map to at most MAX_DAYS entries (day offsets -14..14)
  2. Validate the map size before calling the setter and log/aggregate overflow entries
  3. If you need wider coverage, restrict to the onset window the Exposure Notification API supports

Example fix

// before
builder.setDaysSinceOnsetToInfectiousness(fullYearMap);
// after
Map<Integer, Integer> bounded = fullYearMap.entrySet().stream()
    .filter(e -> e.getKey() >= -14 && e.getKey() <= 14)
    .limit(29)
    .collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue));
builder.setDaysSinceOnsetToInfectiousness(bounded);
Defensive patterns

Strategy: validation

Validate before calling

if (daysMap.size() > 29) {
    throw new IllegalArgumentException("map must have at most 29 day entries (-14..14)");
}
builder.setDaysSinceOnsetToInfectiousness(daysMap);

Try / catch

try {
    builder.setDaysSinceOnsetToInfectiousness(daysMap);
} catch (IllegalArgumentException e) {
    Log.w(TAG, "Day map too large: " + e.getMessage());
}

Prevention

When it happens

Trigger: Passing a Map<Integer,Integer> with more than MAX_DAYS distinct day-offset keys to setDaysSinceOnsetToInfectiousness.

Common situations: Apps build day maps covering a wider window than the 29-day supported range (e.g. generating entries for every possible day programmatically with the wrong bounds).

Understand the failure class

Background: "value must be between 0 and 1" / "out of range" / "must not be negative" errors: fixing range-validation failures across open-source libraries — this error's family across 42 libraries.

Related errors

AI-assisted analysis of microg/GmsCore@157c9d86ac (2026-09-06). Data as JSON: /api/errors/479b8b4cc056474c. Report an issue: GitHub.