"incorrect length" error occurs because your ROM set is outdated for your current version of MAME. Since MAME 0.238
Missing Support Files: Capcom CPS2 games like AvP often require a separate "QSound" BIOS file (e.g., qsound_hle.zip) to function. How to Fix the Error avp14m incorrect length
Protocol Version Mismatch: In rarer instances, the Land Earth Station may be utilizing a newer revision of the AVP14M protocol that includes additional data fields. If the mobile terminal is operating on older firmware that does not recognize these fields, the perceived length of the packet will not align with the expected fixed length of the legacy protocol, triggering a rejection. "incorrect length" error occurs because your ROM set
Overdumped ROMs: Early "dumps" of arcade chips sometimes included extra "junk" data at the end. Modern MAME expects "clean" 1MB versions for avp.14m, 16m, 18m, and 20m. If the mobile terminal is operating on older
