ArduPilot · peterbarker · Sep 1, 2026 · Aug 27, 2026 · Aug 27, 2026 · Aug 27, 2026
diff --git a/AntennaTracker/system.cpp b/AntennaTracker/system.cpp
@@ -46,8 +46,6 @@ void Tracker::init_ardupilot()
 #endif
 
     // initialise rc channels including setting mode
-    // PARAMETER_CONVERSION - Added: Sep-2021 for Tracker-4.5
-    rc().convert_options(RC_Channel::AUX_FUNC::ARMDISARM_UNUSED, RC_Channel::AUX_FUNC::ARMDISARM);
     rc().init();
 
     // initialise servos

diff --git a/ArduCopter/Copter.h b/ArduCopter/Copter.h
@@ -968,10 +968,6 @@ class Copter : public AP_Vehicle {
 
     // Parameters.cpp
     void load_parameters(void) override;
-    void convert_pid_parameters(void);
-#if HAL_PROXIMITY_ENABLED
-    void convert_prx_parameters();
-#endif
 
     // precision_landing.cpp
     void init_precland();

diff --git a/ArduCopter/Parameters.cpp b/ArduCopter/Parameters.cpp
@@ -1271,11 +1271,6 @@ void Copter::load_parameters(void)
 {
     AP_Vehicle::load_parameters(g.format_version, Parameters::k_format_version);
 
-    // PARAMETER_CONVERSION - Added: Mar-2022
-#if AP_FENCE_ENABLED
-    AP_Param::convert_class(g.k_param_fence_old, &fence, fence.var_info, 0, true);
-#endif
-
     // PARAMETER_CONVERSION - Added: Jul-2025 for ArduPilot-4.7
 #if AP_RPM_ENABLED
     AP_Param::convert_class(g.k_param_rpm_sensor_old, &rpm_sensor, rpm_sensor.var_info, 0, true, true);
@@ -1363,88 +1358,3 @@ void Copter::load_parameters(void)
     // setup AP_Param frame type flags
     AP_Param::set_frame_type_flags(AP_PARAM_FRAME_COPTER);
 }
-
-// handle conversion of PID gains
-void Copter::convert_pid_parameters(void)
-{
-    const AP_Param::ConversionInfo angle_and_filt_conversion_info[] = {
-        // PARAMETER_CONVERSION - Added: Aug-2021
-        { Parameters::k_param_pi_vel_xy, 3, AP_PARAM_FLOAT, "PSC_NE_VEL_FLTE" },
-    };
-
-    // convert angle controller gain and filter without scaling
-    for (const auto &info : angle_and_filt_conversion_info) {
-        AP_Param::convert_old_parameter(&info, 1.0f);
-    }
-
-#if AP_INERTIALSENSOR_HARMONICNOTCH_ENABLED
-#if HAL_INS_NUM_HARMONIC_NOTCH_FILTERS > 1
-    if (!ins.harmonic_notches[1].params.enabled()) {
-        // notch filter parameter conversions (moved to INS_HNTC2) for 4.2.x, converted from fixed notch
-        const AP_Param::ConversionInfo notchfilt_conversion_info[] {
-            // PARAMETER_CONVERSION - Added: Apr-2022 for ArduPilot-4.2
-            { Parameters::k_param_ins, 101, AP_PARAM_INT8,  "INS_HNTC2_ENABLE" },
-            { Parameters::k_param_ins, 293, AP_PARAM_FLOAT, "INS_HNTC2_ATT" },
-            { Parameters::k_param_ins, 357, AP_PARAM_FLOAT, "INS_HNTC2_FREQ" },
-            { Parameters::k_param_ins, 421, AP_PARAM_FLOAT, "INS_HNTC2_BW" },
-        };
-        AP_Param::convert_old_parameters(&notchfilt_conversion_info[0], ARRAY_SIZE(notchfilt_conversion_info));
-        AP_Param::set_default_by_name("INS_HNTC2_MODE", 0);
-        AP_Param::set_default_by_name("INS_HNTC2_HMNCS", 1);
-    }
-#endif
-#endif  // AP_INERTIALSENSOR_HARMONICNOTCH_ENABLED
-
-    // ACRO_RP_P and ACRO_Y_P replaced with ACRO_RP_RATE and ACRO_Y_RATE for Copter-4.2
-    // PARAMETER_CONVERSION - Added: Sep-2021
-    const AP_Param::ConversionInfo acro_rpy_conversion_info[] = {
-        { Parameters::k_param_acro_rp_p, 0, AP_PARAM_FLOAT, "ACRO_RP_RATE" },
-        { Parameters::k_param_acro_yaw_p,  0, AP_PARAM_FLOAT, "ACRO_Y_RATE" }
-    };
-    for (const auto &info : acro_rpy_conversion_info) {
-        AP_Param::convert_old_parameter(&info, 45.0);
-    }
-
-    // convert rate and expo command model parameters for Copter-4.3
-    // PARAMETER_CONVERSION - Added: Jun-2022 for ArduPilot-4.3
-    const AP_Param::ConversionInfo cmd_mdl_conversion_info[] = {
-        { Parameters::k_param_g2, 47, AP_PARAM_FLOAT, "ACRO_RP_RATE" },
-        { Parameters::k_param_acro_rp_expo,  0, AP_PARAM_FLOAT, "ACRO_RP_EXPO" },
-        { Parameters::k_param_g2,  48, AP_PARAM_FLOAT, "ACRO_Y_RATE" },
-        { Parameters::k_param_g2,  9, AP_PARAM_FLOAT, "ACRO_Y_EXPO" },
-        { Parameters::k_param_g2,  49, AP_PARAM_FLOAT, "PILOT_Y_RATE" },
-        { Parameters::k_param_g2,  50, AP_PARAM_FLOAT, "PILOT_Y_EXPO" },
-    };
-    for (const auto &info : cmd_mdl_conversion_info) {
-        AP_Param::convert_old_parameter(&info, 1.0);
-    }
-
-    // make any SRV_Channel upgrades needed
-    SRV_Channels::upgrade_parameters();
-}
-
-#if HAL_PROXIMITY_ENABLED
-void Copter::convert_prx_parameters()
-{
-    // convert PRX to PRX1_ parameters for Copter-4.3
-    // PARAMETER_CONVERSION - Added: Aug-2022
-    static const AP_Param::ConversionInfo prx_conversion_info[] = {
-        { Parameters::k_param_g2, 72, AP_PARAM_INT8, "PRX1_TYPE" },
-        { Parameters::k_param_g2, 136, AP_PARAM_INT8, "PRX1_ORIENT" },
-        { Parameters::k_param_g2, 200, AP_PARAM_INT16, "PRX1_YAW_CORR" },
-        { Parameters::k_param_g2, 264, AP_PARAM_INT16, "PRX1_IGN_ANG1" },
-        { Parameters::k_param_g2, 328, AP_PARAM_INT8, "PRX1_IGN_WID1" },
-        { Parameters::k_param_g2, 392, AP_PARAM_INT16, "PRX1_IGN_ANG2" },
-        { Parameters::k_param_g2, 456, AP_PARAM_INT8, "PRX1_IGN_WID2" },
-        { Parameters::k_param_g2, 520, AP_PARAM_INT16, "PRX1_IGN_ANG3" },
-        { Parameters::k_param_g2, 584, AP_PARAM_INT8, "PRX1_IGN_WID3" },
-        { Parameters::k_param_g2, 648, AP_PARAM_INT16, "PRX1_IGN_ANG4" },
-        { Parameters::k_param_g2, 712, AP_PARAM_INT8, "PRX1_IGN_WID4" },
-        { Parameters::k_param_g2, 1224, AP_PARAM_FLOAT, "PRX1_MIN" },
-        { Parameters::k_param_g2, 1288, AP_PARAM_FLOAT, "PRX1_MAX" },
-    };
-    for (const auto &info : prx_conversion_info) {
-        AP_Param::convert_old_parameter(&info, 1.0);
-    }
-}
-#endif
diff --git a/ArduCopter/system.cpp b/ArduCopter/system.cpp
@@ -64,8 +64,6 @@ void Copter::init_ardupilot()
     allocate_motors();
 
     // initialise rc channels including setting mode
-    // PARAMETER_CONVERSION - Added: Sep-2021 for Copter-4.2
-    rc().convert_options(RC_Channel::AUX_FUNC::ARMDISARM_UNUSED, RC_Channel::AUX_FUNC::ARMDISARM_AIRMODE);
     rc().init();
 
     // sets up motors and output to escs
@@ -509,16 +507,10 @@ void Copter::allocate_motors(void)
     }
 
     // upgrade parameters. This must be done after allocating the objects
-    convert_pid_parameters();
 #if FRAME_CONFIG == HELI_FRAME
     motors->heli_motors_param_conversions();
 #endif
 
-#if HAL_PROXIMITY_ENABLED
-    // convert PRX to PRX1_ parameters
-    convert_prx_parameters();
-#endif
-
     // upgrade attitude controller parameters
     copter.attitude_control->convert_parameters();
 

diff --git a/ArduPlane/Parameters.cpp b/ArduPlane/Parameters.cpp
@@ -1305,63 +1305,15 @@ ParametersG2::ParametersG2(void) :
     AP_Param::setup_object_defaults(this, var_info);
 }
 
-/*
-  This is a conversion table from old parameter values to new
-  parameter names. The startup code looks for saved values of the old
-  parameters and will copy them across to the new parameters if the
-  new parameter does not yet have a saved value. It then saves the new
-  value.
-
-  Note that this works even if the old parameter has been removed. It
-  relies on the old k_param index not being removed
-
-  The second column below is the index in the var_info[] table for the
-  old object. This should be zero for top level parameters.
- */
-static const AP_Param::ConversionInfo conversion_table[] = {
-    // PARAMETER_CONVERSION - Added: Mar-2021 for ArduPlane-4.1
-    { Parameters::k_param_fence_minalt,       0,     AP_PARAM_INT16, "FENCE_ALT_MIN"},
-    { Parameters::k_param_fence_maxalt,       0,     AP_PARAM_INT16, "FENCE_ALT_MAX"},
-    { Parameters::k_param_fence_retalt,       0,     AP_PARAM_INT16, "FENCE_RET_ALT"},
-    { Parameters::k_param_fence_ret_rally,    0,      AP_PARAM_INT8, "FENCE_RET_RALLY"},
-    { Parameters::k_param_fence_autoenable,   0,      AP_PARAM_INT8, "FENCE_AUTOENABLE"},
-};
-
-struct RCConversionInfo {
-    uint16_t old_key; // k_param_*
-    uint32_t old_group_element; // index in old object
-    RC_Channel::AUX_FUNC fun; // new function
-};
-
-static const RCConversionInfo rc_option_conversion[] = {
-    { Parameters::k_param_flapin_channel_old, 0, RC_Channel::AUX_FUNC::FLAP},
-    { Parameters::k_param_g2, 968, RC_Channel::AUX_FUNC::SOARING},
-#if AP_FENCE_ENABLED
-    { Parameters::k_param_fence_channel, 0, RC_Channel::AUX_FUNC::FENCE},
-#endif
-#if AP_MISSION_ENABLED
-    { Parameters::k_param_reset_mission_chan, 0, RC_Channel::AUX_FUNC::MISSION_RESET},
-#endif
-#if HAL_PARACHUTE_ENABLED
-    { Parameters::k_param_parachute_channel, 0, RC_Channel::AUX_FUNC::PARACHUTE_RELEASE},
-#endif
-    { Parameters::k_param_fbwa_tdrag_chan, 0, RC_Channel::AUX_FUNC::FBWA_TAILDRAGGER},
-    { Parameters::k_param_reset_switch_chan, 0, RC_Channel::AUX_FUNC::MODE_SWITCH_RESET},
-};
-
 void Plane::load_parameters(void)
 {
     AP_Vehicle::load_parameters(g.format_version, Parameters::k_format_version);
 
-    AP_Param::convert_old_parameters(&conversion_table[0], ARRAY_SIZE(conversion_table));
-
     // setup defaults in SRV_Channels
     g2.servo_channels.set_default_function(CH_1, SRV_Channel::k_aileron);
     g2.servo_channels.set_default_function(CH_2, SRV_Channel::k_elevator);
     g2.servo_channels.set_default_function(CH_3, SRV_Channel::k_throttle);
     g2.servo_channels.set_default_function(CH_4, SRV_Channel::k_rudder);
-
-    SRV_Channels::upgrade_parameters();
 
 #if HAL_QUADPLANE_ENABLED
     if (quadplane.enable) {
@@ -1372,151 +1324,9 @@ void Plane::load_parameters(void)
 
     AP_Param::set_frame_type_flags(AP_PARAM_FRAME_PLANE);
 
-    // Convert chan params to RCx_OPTION
-    // PARAMETER_CONVERSION - Added: Mar-2021 for ArduPlane-4.1
-    for (uint8_t i=0; i<ARRAY_SIZE(rc_option_conversion); i++) {
-        AP_Int8 chan_param;
-        AP_Param::ConversionInfo info {rc_option_conversion[i].old_key, rc_option_conversion[i].old_group_element, AP_PARAM_INT8, nullptr};
-        if (AP_Param::find_old_parameter(&info, &chan_param) && chan_param.get() > 0) {
-            RC_Channel *chan = rc().channel(chan_param.get() - 1);
-            if (chan != nullptr && !chan->option.configured()) {
-                chan->option.set_and_save((int16_t)rc_option_conversion[i].fun); // save the new param
-            }
-        }
-    }
-
-
-// PARAMETER_CONVERSION - Added: Mar-2021 for ArduPlane-4.1
-#if AP_FENCE_ENABLED
-    enum ap_var_type ptype_fence_type;
-    AP_Int8 *fence_type_new = (AP_Int8*)AP_Param::find("FENCE_TYPE", &ptype_fence_type);
-    if (fence_type_new && !fence_type_new->configured()) {
-        // If we find the new parameter and it hasn't been configured
-        // attempt to upgrade the altitude fences.
-        int8_t fence_type_new_val = AC_FENCE_TYPE_POLYGON;
-        AP_Int16 fence_alt_min_old;
-        AP_Param::ConversionInfo fence_alt_min_info_old = {
-            Parameters::k_param_fence_minalt,
-            0,
-            AP_PARAM_INT16,
-            nullptr
-        };
-        if (AP_Param::find_old_parameter(&fence_alt_min_info_old, &fence_alt_min_old)) {
-            if (fence_alt_min_old.configured()) {
-                //
-                fence_type_new_val |= AC_FENCE_TYPE_ALT_MIN;
-            }
-        }
-
-        AP_Int16 fence_alt_max_old;
-        AP_Param::ConversionInfo fence_alt_max_info_old = {
-            Parameters::k_param_fence_maxalt,
-            0,
-            AP_PARAM_INT16,
-            nullptr
-        };
-        if (AP_Param::find_old_parameter(&fence_alt_max_info_old, &fence_alt_max_old)) {
-            if (fence_alt_max_old.configured()) {
-                fence_type_new_val |= AC_FENCE_TYPE_ALT_MAX;
-            }
-        }
-
-        fence_type_new->set_and_save((int8_t)fence_type_new_val);
-    }
-
-    AP_Int8 fence_action_old;
-    AP_Param::ConversionInfo fence_action_info_old = {
-        Parameters::k_param_fence_action,
-        0,
-        AP_PARAM_INT8,
-        "FENCE_ACTION"
-    };
-    if (AP_Param::find_old_parameter(&fence_action_info_old, &fence_action_old)) {
-        enum ap_var_type ptype;
-        AP_Int8 *fence_action_new = (AP_Int8*)AP_Param::find(&fence_action_info_old.new_name[0], &ptype);
-        AC_Fence::Action fence_action_new_val;
-        if (fence_action_new && !fence_action_new->configured()) {
-            switch(fence_action_old.get()) {
-                case 0: // FENCE_ACTION_NONE
-                case 2: // FENCE_ACTION_REPORT_ONLY
-                default:
-                    fence_action_new_val = AC_Fence::Action::REPORT_ONLY;
-                    break;
-                case 1: // FENCE_ACTION_GUIDED
-                    fence_action_new_val = AC_Fence::Action::GUIDED;
-                    break;
-                case 3: // FENCE_ACTION_GUIDED_THR_PASS
-                    fence_action_new_val = AC_Fence::Action::GUIDED_THROTTLE_PASS;
-                    break;
-                case 4: // FENCE_ACTION_RTL
-                    fence_action_new_val = AC_Fence::Action::RTL_AND_LAND;
-                    break;
-            }
-            fence_action_new->set_and_save((int8_t)fence_action_new_val);
-
-            // Now upgrade the new fence enable at the same time
-            enum ap_var_type ptype_fence_enable;
-            AP_Int8 *fence_enable = (AP_Int8*)AP_Param::find("FENCE_ENABLE", &ptype_fence_enable);
-            // fences were used if there was a count, and the old fence action was not zero
-            AC_Fence *ap_fence = AP::fence();
-            bool fences_exist = false;
-            if (ap_fence) {
-                // If the fence library is present, attempt to read the fence count
-                fences_exist = ap_fence->polyfence().total_fence_count() > 0;
-            }
-
-            bool fences_used = fence_action_old.get() != 0;
-            if (fence_enable && !fence_enable->configured()) {
-                // The fence enable parameter exists, so now set it accordingly
-                fence_enable->set_and_save(fences_exist && fences_used);
-            }
-        }
-    }
-#endif // AP_FENCE_ENABLED
-
-#if AP_TERRAIN_AVAILABLE
-    // PARAMETER_CONVERSION - Added: Mar-2021 for ArduPlane-4.1
-    g.terrain_follow.convert_parameter_width(AP_PARAM_INT8);
-#endif
-
-    // PARAMETER_CONVERSION - Added: Jun-2021 for ArduPlane-4.1
-    g.use_reverse_thrust.convert_parameter_width(AP_PARAM_INT16);
-
     // PARAMETER_CONVERSION - Added: Jun-2026 for FBWB_CLIMB_RATE width change
     g.flybywire_climb_rate.convert_parameter_width(AP_PARAM_INT8);
 
-#if AP_AIRSPEED_ENABLED
-    // PARAMETER_CONVERSION - Added: Jan-2022
-    {
-        const uint16_t old_key = g.k_param_airspeed;
-        const uint16_t old_index = 0;       // Old parameter index in the tree
-        AP_Param::convert_class(old_key, &airspeed, airspeed.var_info, old_index, true);
-    }
-#endif
-
-#if AP_INERTIALSENSOR_HARMONICNOTCH_ENABLED
-#if HAL_INS_NUM_HARMONIC_NOTCH_FILTERS > 1
-    if (!ins.harmonic_notches[1].params.enabled()) {
-        // notch filter parameter conversions (moved to INS_HNTC2) for 4.2.x, converted from fixed notch
-        const AP_Param::ConversionInfo notchfilt_conversion_info[] {
-            // PARAMETER_CONVERSION - Added: Apr-2022 for ArduPlane-4.2
-            { Parameters::k_param_ins, 101, AP_PARAM_INT8,  "INS_HNTC2_ENABLE" },
-            { Parameters::k_param_ins, 293, AP_PARAM_FLOAT, "INS_HNTC2_ATT" },
-            { Parameters::k_param_ins, 357, AP_PARAM_FLOAT, "INS_HNTC2_FREQ" },
-            { Parameters::k_param_ins, 421, AP_PARAM_FLOAT, "INS_HNTC2_BW" },
-        };
-        AP_Param::convert_old_parameters(&notchfilt_conversion_info[0], ARRAY_SIZE(notchfilt_conversion_info));
-        AP_Param::set_default_by_name("INS_HNTC2_MODE", 0);
-        AP_Param::set_default_by_name("INS_HNTC2_HMNCS", 1);
-    }
-#endif // HAL_INS_NUM_HARMONIC_NOTCH_FILTERS
-#endif  // AP_INERTIALSENSOR_HARMONICNOTCH_ENABLED
-
-    // PARAMETER_CONVERSION - Added: Mar-2022
-#if AP_FENCE_ENABLED
-    AP_Param::convert_class(g.k_param_fence, &fence, fence.var_info, 0, true);
-#endif
-
     // PARAMETER_CONVERSION - Added: Jul-2025 for ArduPilot-4.7
 #if AP_RPM_ENABLED
     AP_Param::convert_class(g.k_param_rpm_sensor_old, &rpm_sensor, rpm_sensor.var_info, 0, true, true);
@@ -1541,10 +1351,6 @@ void Plane::load_parameters(void)
     landing.convert_parameters();
 
     static const AP_Param::G2ObjectConversion g2_conversions[] {
-    // PARAMETER_CONVERSION - Added: Oct-2021
-#if HAL_EFI_ENABLED
-        { &efi, efi.var_info, 22 },
-#endif
 #if AP_STATS_ENABLED
     // PARAMETER_CONVERSION - Added: Jan-2024 for Plane-4.6
         { &stats, stats.var_info, 5 },