stride3d/stride · error · InvalidOperationException

Unable to read asset index entry

Error message

Unable to read asset index entry [{0}]. Expecting: [path objectId]

What it means

ContentIndexMap.ReadEntries parses a text index file where every non-comment line must match the pattern 'path objectId' (matched by regexEntry). A line that does not match means the index file is malformed, so ReadEntries throws InvalidOperationException naming the offending line.

Solutions

Open the index file and fix or remove the malformed line so it reads 'path objectId'
Restore the index file from backup or regenerate it by re-saving the assets/package
Check for a trailing partial line from an interrupted write and delete it

Example fix

// before (index file)
assets/myasset
# missing objectId
// after
assets/myasset 0123456789abcdef0123456789abcdef

Defensive patterns

Strategy: try-catch

Validate before calling

static bool IsValidIndexLine(string line, Regex regexEntry) =>
    line.Length == 0 || line.StartsWith('#') || regexEntry.IsMatch(line);

Try / catch

try { contentIndexMap.Load(); }
catch (InvalidOperationException ex) when (ex.Message.StartsWith("Unable to read asset index entry"))
{
    Log.Error(ex, "Corrupt index file; regenerating from source assets");
    // rebuild or restore the index
}

Prevention

Never hand-edit index files; use library APIs to modify them
Validate/backup the index before large operations
Handle crash recovery by truncating partial trailing lines
Keep index format consistent across Stride versions

When it happens

Trigger: A truncated or hand-edited index file; a line with missing ObjectId, extra fields, or an unescaped path containing the separator; output written by an incompatible older/newer format.

Common situations: Crash or disk-full left a partial last line; manual editing of the .idx file; merging index files from different Stride versions.

Understand the failure class

Background: Schema validation failed / invalid input schema: payload rejected because its shape doesn't match the expected schema — this error's family across 28 libraries.

Related errors

AI-assisted analysis of stride3d/stride@96fad776d2 (2026-09-14). Data as JSON: /api/errors/09951f15720161a3. Report an issue: GitHub.

Appendix: source

Thrown at sources/core/Stride.Core.Serialization/Serialization/Contents/ContentIndexMap.cs:115

        }
    }

    protected override List<KeyValuePair<string, ObjectId>> ReadEntries(Stream localStream)
    {
        ArgumentNullException.ThrowIfNull(localStream);

        var reader = new StreamReader(localStream, Encoding.UTF8);
        var entries = new List<KeyValuePair<string, ObjectId>>();
        while (reader.ReadLine() is { } line)
        {
            line = line.Trim();
            if (line.Length == 0 || line.StartsWith('#'))
                continue;

            var match = regexEntry.Match(line);
            if (!match.Success)
            {
                throw new InvalidOperationException("Unable to read asset index entry [{0}]. Expecting: [path objectId]".ToFormat(line));
            }

            var url = match.Groups[1].Value;
            var objectIdStr = match.Groups[2].Value;

            // Test if the name has leading or ending spaces
            var matchSpace = regexEntrySpace.Match(line);
            if (matchSpace.Success && !matchSpace.Groups[1].Value.Equals(url))
            {
                throw new InvalidOperationException("Assets names cannot have empty spaces before or after the name. Please rename [{0}] and compile again.".ToFormat(matchSpace.Groups[1].Value));
            }

            if (!ObjectId.TryParse(objectIdStr, out var objectId))
            {
                throw new InvalidOperationException("Unable to decode objectid [{0}] when reading asset index".ToFormat(objectIdStr));
            }

            var entry = new KeyValuePair<string, ObjectId>(url, objectId);

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