1. Symptoms
The clw-prompt-oom error occurs when the input prompt submitted to OpenClaw exceeds the configured or system-imposed memory allocation for prompt processing. Users encounter this error during normal operations when attempting to process large text inputs, batch operations, or complex multi-line prompts that consume more memory than the application has available or is willing to allocate.
The characteristic shell output when this error manifests typically appears as follows:
[ERROR] clw-prompt-oom: Prompt input exceeds available memory allocation
Prompt size: 45.2 MB
Available memory: 32.0 MB
Suggestion: Reduce prompt size or increase memory limit
In interactive mode, the error presents with additional context about the current session state:
OpenClaw CLI v2.4.1
Session ID: sess_8a7b3c2d
Prompt processing failed: clw-prompt-oom
Memory allocation summary:
- Peak usage: 89.5 MB
- Limit: 64.0 MB
- Prompt overhead: 25.5 MB
Consider splitting your input into smaller chunks.
Additional observable symptoms include sudden process termination without graceful cleanup, potential loss of unsaved work in interactive sessions, and degraded system performance on machines with limited RAM when the error occurs. In automated pipelines, this error typically causes non-zero exit codes that break CI/CD workflows, making it critical to address proactively rather than reactively.
2. Root Cause
The clw-prompt-oom error stems from fundamental memory allocation constraints within the OpenClaw runtime environment. Understanding the architecture reveals why this limitation exists and how it manifests across different usage patterns.
OpenClaw processes prompts by loading the entire input into memory before parsing, validation, and execution. This design choice optimizes for low-latency response on typical inputs but creates vulnerability when processing unusually large inputs. The underlying cause involves three interconnected factors: the fixed memory ceiling configured during installation, the cumulative memory footprint of the current session state, and the nature of the input being processed.
In OpenClaw’s internal architecture, each prompt undergoes several memory-intensive operations. First, the raw input string occupies memory proportional to its size. Second, the parsing engine creates intermediate abstract syntax representations that can exceed the original input size by a factor of two to five times. Third, variable expansion and template processing create additional allocations. Fourth, session context including history and state information adds persistent overhead that compounds across multiple interactions.
The 64-megabyte default limit, while generous for typical command-line operations, becomes restrictive when users attempt to process configuration files, log dumps, codebases, or batch instructions that approach or exceed this boundary. Furthermore, the memory limit applies to the combined footprint of the prompt, parsed representation, and session context—not merely the raw input size. This aggregate calculation often surprises users who expect the limit to refer only to the visible input text.
On systems with constrained resources, the effective limit may be further reduced by system-wide memory pressure, container cgroup restrictions, or competing processes consuming available RAM. The error triggers when the combined memory requirement exceeds the lower of either the configured limit or the available system memory, whichever constraint becomes binding first.
3. Step-by-Step Fix
Resolving the clw-prompt-oom error requires addressing either the input size, the memory configuration, or both. Follow this systematic approach to identify and implement the appropriate solution for your environment.
Step 1: Diagnose Input Size and Memory Status
Before modifying configuration, quantify the actual memory consumption to determine whether the issue stems from legitimately large inputs or unnecessarily verbose prompts.
# Check current prompt size in bytes
wc -c your-input-file.txt
# Run OpenClaw with verbose memory reporting
clw --verbose --memory-report process --prompt "$(cat large-prompt.txt)"
# Inspect current memory configuration
clw config get memory.limit
clw config get memory.session_overhead
Step 2: Reduce Prompt Size
If your input exceeds reasonable limits, trim the content to essential elements. This approach is preferable to increasing memory limits because it improves performance and reduces resource consumption.
Before:
Process the following 500-line configuration file and apply changes to each section:
[Entire 500-line configuration file content embedded directly in prompt]
After:
Process the configuration directives in config-revised.txt and apply the security
hardening profile. Focus on sections: authentication, encryption, and logging.
Step 3: Increase Memory Limit
If legitimate use cases require larger prompts, adjust the memory allocation:
# View all memory-related configuration options
clw config list | grep -i memory
# Set a higher memory limit (example: 128 MB)
clw config set memory.limit 128M
# Set limit with explicit unit specification
clw config set memory.limit 256
# Verify the new configuration
clw config get memory.limit
Step 4: Configure Session-Based Limits
For long-running interactive sessions, reduce accumulated overhead by clearing history or resetting session state:
# Clear session history to free accumulated memory
clw session clear-history
# Start fresh session with clean state
clw session reset
# Set maximum session history entries
clw config set memory.max_history 50
Step 5: Implement Chunked Processing
For inputs that genuinely require large amounts of data, restructure operations to process in chunks:
# Split large input into manageable pieces
split -b 10M large-input.txt chunk_
# Process each chunk sequentially
for chunk in chunk_*; do
clw process --prompt "$(cat "$chunk")" --output "${chunk}.out"
done
# Merge results
cat chunk_*.out > final-output.txt
Step 6: Set System-Level Overrides
For persistent environments where default limits remain problematic, configure system-wide settings:
Linux/macOS:
# Set environment variable for enhanced memory allocation
export CLW_MEMORY_LIMIT=256M
clw process --prompt "your input"
Windows (PowerShell):
$env:CLW_MEMORY_LIMIT = "256M"
clw process --prompt "your input"
4. Verification
After implementing fixes, verification ensures the error no longer occurs and performance remains acceptable. This validation process should confirm both successful processing and appropriate resource utilization.
First, test with a moderately-sized input that previously triggered the error:
# Test with a moderately large input (around 40 MB if limit is 64 MB)
clw process --prompt "$(head -c 40M test-data.txt)"
# Verify successful completion
echo $? # Should output 0 for success
Second, confirm memory configuration changes took effect:
# Check effective memory limit including environment overrides
clw config show --effective | grep -A5 memory
# Verify no warnings during processing
clw process --prompt "test" --log-level warn
Third, monitor actual memory consumption during processing:
# Enable memory tracking during execution
clw --memory-tracking process --prompt "your input"
# Check peak memory usage in output
# Should remain below configured limit with margin for overhead
Fourth, validate chunked processing produces consistent results:
# Compare checksum of single-pass processing versus chunked processing
# These should match for deterministic operations
clw process --prompt "$(cat small-test.txt)" --output single.out
clw process --prompt "$(cat small-test.txt)" --output chunk-compare.out
diff single.out chunk-compare.out
Fifth, perform load testing to ensure stability under realistic conditions:
# Run multiple sequential operations to verify no memory leaks
for i in {1..100}; do
clw process --prompt "Iteration $i test" > /dev/null 2>&1
done
echo "Completed 100 iterations without memory growth"
5. Common Pitfalls
Several recurring mistakes complicate resolution of the clw-prompt-oom error. Awareness of these pitfalls enables faster diagnosis and prevents wasted effort on ineffective solutions.
Misunderstanding the Memory Limit Scope: Many users assume the configured memory limit applies only to raw input size. In reality, the limit encompasses the parsed representation, session context, and intermediate processing artifacts. An input that appears to fit within the limit may still trigger the error because parsing overhead multiplies memory requirements. Always include a safety margin of at least 30 percent when estimating whether an input will fit.
Ignoring Session Accumulation: Interactive sessions retain history and state that contribute to memory consumption. Users who run many commands in a single session may find that inputs that previously succeeded now fail due to accumulated overhead. Regularly clearing session history or periodically restarting the CLI prevents this gradual memory exhaustion pattern.
Setting Limits Too Aggressively: While raising the memory limit solves immediate errors, setting excessively high limits without corresponding system resources causes swapping that degrades overall system performance. The limit should reflect realistic available memory on your target deployment environment.
Using File References Instead of Inline Content: When processing large files, passing content directly via command substitution ($(cat file.txt)) loads the entire file into memory twice—once for substitution and once for OpenClaw processing. Using --file flags or piping with appropriate buffering is more memory-efficient:
# Memory-inefficient approach
clw process --prompt "$(cat huge-file.txt)"
# Memory-efficient approach
clw process --file huge-file.txt
# Or piped with buffering
cat huge-file.txt | clw process --prompt-from-stdin
Neglecting Container and Environment Limits: When running OpenClaw inside Docker, Kubernetes, or other containerized environments, container memory limits may be stricter than the OpenClaw configuration. The application will hit container limits before reaching OpenClaw’s configured ceiling, causing unpredictable failures. Always align container resource limits with application requirements.
6. Related Errors
The clw-prompt-oom error belongs to a family of memory and input-related failures in OpenClaw. Understanding related errors provides context for comprehensive troubleshooting and helps identify whether symptoms might indicate a different underlying issue.
clw-buffer-overflow: This error occurs when writing processed output exceeds allocated buffer space, typically during operations that produce substantially more data than the input. Unlike clw-prompt-oom which addresses input memory, buffer overflow errors relate to output handling. Symptoms include truncated output files and warnings about output size limits. The fix involves either streaming output to disk, increasing buffer allocations, or restructuring operations to process incrementally.
clw-input-truncated: This error indicates that input was forcibly shortened before processing, potentially causing incorrect results or missed operations. Unlike the memory exhaustion of clw-prompt-oom, truncation errors suggest configuration limits are too restrictive for legitimate use cases. Users typically observe incomplete processing and missing sections in output. Increasing input size limits or pre-processing inputs to remove unnecessary content resolves this issue.
clw-session-limit: This error occurs when the number of concurrent sessions or the total session duration exceeds configured thresholds. While related to resource management like clw-prompt-oom, session limits address session-level constraints rather than memory-per-operation limits. Users running automated pipelines or long-running interactive sessions commonly encounter this error. Adjusting session timeout values, cleaning up completed sessions, or increasing session limits in configuration addresses the underlying constraint.