Firmware version 8.3.6 replaces the base firmware version 8.3.3 for the HP 2500 series printers. The improvements over the previous firmware are as follows : 1. Fixes to reduce the occurrence of acumen errors 23 and 24 (ACU_FAIL_TEMP_TOO_HIGH, ACU_FAIL_TEMP_TOO_LOW respectively). The lower threshold is now lowered by 5degC compared to FW8.3.3, the upper threshold increased by 5degC compared to FW8.3.3. 2. The firmware includes an improved algorithm to ensure a more robust printhead error messages. 3. Tray 1 media present LCD message now has localised equivalents.