Blender 2.82 - installed addon is not working after blender restart

Question

I have this simple script for exporting meshes. It's all in one file and works fine (no errors) when executed from the scripting editor.

When I am installing it through "Preferences -> Install from file" it shows up in the list, I enable it, but it wont work untill I run it in the script editor, in blender.

The same goes after restarting Blender - it's visible in the list as enbaled but does not work. I need to run it through script editor to activate.

I checked user scripts folder for addon and it's there, so installation process went ok.

Windows 10.

How to fix it? Thanks

Code:

bl_info = {"name" : "Spike FBX Unity Export",   "category": "Export",   "author": "Sergiusz"}

import bpy
import os

from bpy_extras.io_utils import ExportHelper

class Spk_Object_Settings(bpy.types.PropertyGroup):
    layer: bpy.props.StringProperty(default="spk_EnviroStatic")
    collider: bpy.props.EnumProperty(
        name = "Collider",
        items = (("None", "None", ""), ("Box", "Box", ""), ("Sphere", "Sphere", ""), ("Capsule", "Capsule", ""), ("Mesh", "Mesh", "")), default = "Mesh")

#====

class Spk_PT_Object_Settings(bpy.types.Panel):
    bl_idname = "spike.object_settings_panel"
    bl_label = "Object Settings"
    bl_space_type = "VIEW_3D"
    bl_region_type = "UI"
    bl_category = "Spike"

    @classmethod
    def poll(cls, context):
        return (context.selected_objects != []) and (context.active_object.type == "MESH")

    def draw(self, context):
        layout = self.layout

        o = bpy.context.active_object

        box = layout.box()
        box.prop(o.data.Spk_Object_Settings, "layer", text = "Layer")
        box.prop(o.data.Spk_Object_Settings, "collider", text = "Collider")

#====

class Spk_OT_Fbx_Export(bpy.types.Operator, ExportHelper):
    bl_idname = "spike.fbx_export"
    bl_label = "Spike FBX Unity Export"

    filename_ext = ".fbx"

    filter_glob: bpy.props.StringProperty(
        default="*.fbx",
        options={'HIDDEN'},
        maxlen=255,  # Max internal buffer length, longer would be clamped.
    )

    @classmethod
    def poll(cls, context):
        return (context.selected_objects != []) and (context.active_object.type == "MESH")

    def execute(self, context):
        folder_path = (os.path.dirname(self.filepath))

        if folder_path == None:
            self.report({'ERROR'}, "Export folder not set")
        else:
            objs = bpy.context.selected_objects

            for o in objs:
                o.select_set(False)

            for o in objs:
                if o.type == "MESH":

                    print("Exporting: " + o.name + "...")

                    o["spk_export_layer"] = o.data.Spk_Object_Settings.layer
                    o["spk_export_collider"] = o.data.Spk_Object_Settings.collider

                    file_path = folder_path + "/" + o.name + ".fbx"

                    o.select_set(True)
                    bpy.context.view_layer.objects.active = o

                    bpy.ops.export_scene.fbx(
                        filepath = file_path,
                        use_selection = True,
                        global_scale = 1.0,
                        apply_unit_scale = True,
                        apply_scale_options = 'FBX_SCALE_NONE',
                        mesh_smooth_type = 'OFF',
                        bake_space_transform = True,
                        bake_anim = False,
                        object_types = {'MESH'},
                        use_tspace = True,
                        use_mesh_modifiers = True,
                        use_custom_props  = True,
                        axis_forward = '-Z',
                        axis_up = 'Y')

                    print("Exporting: ...done")

                    o.select_set(False)
#            self.report({"INFO"}, "Will export: " + (context.active_object.name) + " to: " + (folder_path))

            for o in objs:
                o.select_set(True)
        return {'FINISHED'}


classes = (Spk_OT_Fbx_Export, Spk_Object_Settings, Spk_PT_Object_Settings)

def menu_func_export(self, context):
    self.layout.operator(Spk_OT_Fbx_Export.bl_idname, text="Spike FBX Unity Export")

def register():
    for c in classes:
        bpy.utils.register_class(c)

    bpy.types.Mesh.Spk_Object_Settings = bpy.props.PointerProperty(type=Spk_Object_Settings)

    bpy.types.TOPBAR_MT_file_export.append(menu_func_export)

def unregister():
    bpy.utils.unregister_classes_factory(classes)

    bpy.types.TOPBAR_MT_file_export.remove(menu_func_export)

if __name__ == "__main__": register()

Answer 1

Your Version Info (bl_info dict) is incomplete. Add a version number and especially the blender release. If not greater than 2,8,0 blender is going to ignore the addon. From Blender 2.80: Python API Changes:

Make sure the "blender" key in the bl_info dictionary is set to:

(2, 80, 0) not (2, 8, 0) or (2, 79, 0) Example: "blender": (2, 80, 0), for Otherwise, this error is reported:

Exception: Add-on 'ADDON_NAME' has not been upgraded to 2.8, ignoring

Reference

bl_info = {
    "name": "Your cool add-on name",
    "author": "Your cool author name",
    "version": (0, 1, 0),
    "blender": (2, 80, 0),
    "location": "Where the user can find it",
    "description": "What the add-on does",
    "warning": "",
    "wcooliki_url": "",
    "tracker_url": "",
    "category": ""}

---

I also suggest use os.path.join() for all file paths and un-register your classes properly (returns another error). Read and compare to Exporting multiple meshes individually at once, which is basically the same add-on, exporting fbx files to unity.