# Warning: PHP Startup: Unable to allocate interned strings buffer: 2097152 bytes in Unknown on line 0

- **ID:** `php/opcache-interned-strings-buffer`
- **Domain:** php
- **Category:** system_error
- **Verification:** ai_generated
- **Fix Rate:** 90%

## Root Cause

OPcache's interned strings buffer is too large for the available shared memory, typically due to a misconfigured `opcache.interned_strings_buffer` value exceeding the system's shared memory limits.

## Version Compatibility

| Version | Status | Introduced | Deprecated |
|---------|--------|------------|------------|
| PHP 8.0 | active | — | — |
| PHP 8.1 | active | — | — |
| PHP 8.2 | active | — | — |
| PHP 8.3 | active | — | — |
| OPcache 8.0 | active | — | — |
| OPcache 8.1 | active | — | — |

## Workarounds

1. **Reduce `opcache.interned_strings_buffer` in php.ini to a smaller value, e.g., from 16 to 8: `opcache.interned_strings_buffer = 8`** (90% success)
   ```
   Reduce `opcache.interned_strings_buffer` in php.ini to a smaller value, e.g., from 16 to 8: `opcache.interned_strings_buffer = 8`
   ```
2. **Increase the system shared memory limit by modifying `/etc/sysctl.conf` with `kernel.shmmax = 2147483648` and `kernel.shmall = 2097152`, then reload with `sysctl -p`.** (75% success)
   ```
   Increase the system shared memory limit by modifying `/etc/sysctl.conf` with `kernel.shmmax = 2147483648` and `kernel.shmall = 2097152`, then reload with `sysctl -p`.
   ```
3. **Check available shared memory with `ipcs -lm` and adjust `opcache.interned_strings_buffer` to a value that fits within the system limits; a safe starting point is 4 MB.** (85% success)
   ```
   Check available shared memory with `ipcs -lm` and adjust `opcache.interned_strings_buffer` to a value that fits within the system limits; a safe starting point is 4 MB.
   ```

## Dead Ends

- **** — The error is about allocation failure; increasing the value increases memory demand. (95% fail)
- **** — The error only affects startup; disabling OPcache is unnecessary if the buffer size is adjusted. (60% fail)
- **** — The issue is a persistent configuration problem, not a transient system state. (90% fail)