OK, here is the debug from the 2.81a tarball, in two posts, and the blender.crash.txt.
Unzipped, placed in the same home .blender folder as 2.79b that still works, in it’s own folder.
Won’t start. But 2.79b still does.
# Blender 2.81 (sub 16), Commit date: 2019-12-04 11:32, Hash f1aa4d18d49d
# backtrace
/home/dad/.blender/blender-2.81a-linux-glibc217-x86_64/blender(BLI_system_backtrace+0x1d) [0x14ee84d]
/home/dad/.blender/blender-2.81a-linux-glibc217-x86_64/blender() [0x12cbb79]
/lib64/libc.so.6(+0x3be10) [0x7fe787775e10]
/home/dad/.blender/blender-2.81a-linux-glibc217-x86_64/blender(GPU_draw_list_command_add+0x58) [0x4591758]
/home/dad/.blender/blender-2.81a-linux-glibc217-x86_64/blender() [0x2cfe2e0]
/home/dad/.blender/blender-2.81a-linux-glibc217-x86_64/blender() [0x2cff67f]
/home/dad/.blender/blender-2.81a-linux-glibc217-x86_64/blender(workbench_deferred_draw_scene+0x4f2) [0x2d2db42]
/home/dad/.blender/blender-2.81a-linux-glibc217-x86_64/blender() [0x2d2a34b]
/home/dad/.blender/blender-2.81a-linux-glibc217-x86_64/blender(DRW_draw_render_loop_ex+0x274) [0x2cf8b84]
/home/dad/.blender/blender-2.81a-linux-glibc217-x86_64/blender(view3d_main_region_draw+0x77) [0x2fd7137]
/home/dad/.blender/blender-2.81a-linux-glibc217-x86_64/blender(ED_region_do_draw+0x8f1) [0x304b9d1]
/home/dad/.blender/blender-2.81a-linux-glibc217-x86_64/blender(wm_draw_update+0x496) [0x16a0686]
/home/dad/.blender/blender-2.81a-linux-glibc217-x86_64/blender(WM_main+0x30) [0x169dce0]
/home/dad/.blender/blender-2.81a-linux-glibc217-x86_64/blender(main+0x2fe) [0x1237f7e]
/lib64/libc.so.6(__libc_start_main+0xeb) [0x7fe787760b7b]
/home/dad/.blender/blender-2.81a-linux-glibc217-x86_64/blender() [0x12c84
dad@dad-Cinnamon:~> blender --debug-all
Switching to fully guarded memory allocator.
read file
Version 280 sub 39 date unknown hash unknown
DEG_relations_tag_update: Tagging relations for update.
DEG_relations_tag_update: Tagging relations for update.
DEG_relations_tag_update: Tagging relations for update.
DEG_relations_tag_update: Tagging relations for update.
DEG_relations_tag_update: Tagging relations for update.
graph_id_tag_update: id=SCScene flags=LEGACY_0 source=USER_EDIT
Received X11 Error:
error code: 170
request code: 152
minor code: 34
error text: GLXBadFBConfig
Received X11 Error:
error code: 170
request code: 152
minor code: 34
error text: GLXBadFBConfig
Received X11 Error:
error code: 170
request code: 152
minor code: 34
error text: GLXBadFBConfig
Received X11 Error:
error code: 170
request code: 152
minor code: 34
error text: GLXBadFBConfig
Received X11 Error:
error code: 170
request code: 152
minor code: 34
error text: GLXBadFBConfig
Received X11 Error:
error code: 170
request code: 152
minor code: 34
error text: GLXBadFBConfig
ED_screen_refresh: set screen
graph_id_tag_update: id=SCScene flags=TRANSFORM, GEOMETRY, SHADING, SELECT, BASE_FLAGS, POINT_CACHE, COPY_ON_WRITE, SEQUENCER_STRIPS, AUDIO_SEEK, AUDIO_FPS, AUDIO_VOLUME, AUDIO_MUTE, AUDIO_LISTENER, AUDIO, PARAMETERS source=RELATIONS
graph_id_tag_update: id=OBCube flags=TRANSFORM, GEOMETRY, COPY_ON_WRITE source=RELATIONS
graph_id_tag_update: id=MECube flags=LEGACY_0 source=RELATIONS
graph_id_tag_update: id=MECube flags=COPY_ON_WRITE source=RELATIONS
graph_id_tag_update: id=MAMaterial flags=COPY_ON_WRITE source=RELATIONS
graph_id_tag_update: id=NTShader Nodetree flags=COPY_ON_WRITE source=RELATIONS
graph_id_tag_update: id=NTShader Nodetree flags=COPY_ON_WRITE source=RELATIONS
graph_id_tag_update: id=OBLight flags=TRANSFORM, GEOMETRY, COPY_ON_WRITE source=RELATIONS
graph_id_tag_update: id=LALight flags=COPY_ON_WRITE source=RELATIONS
graph_id_tag_update: id=OBCamera flags=TRANSFORM, GEOMETRY, COPY_ON_WRITE source=RELATIONS
graph_id_tag_update: id=CACamera flags=COPY_ON_WRITE source=RELATIONS
graph_id_tag_update: id=GRMaster Collection flags=COPY_ON_WRITE source=RELATIONS
graph_id_tag_update: id=GRCollection flags=COPY_ON_WRITE source=RELATIONS
graph_id_tag_update: id=WOWorld flags=COPY_ON_WRITE source=RELATIONS
graph_id_tag_update: id=NTShader Nodetree flags=COPY_ON_WRITE source=RELATIONS
graph_id_tag_update: id=NTShader Nodetree flags=COPY_ON_WRITE source=RELATIONS
graph_id_tag_update: id=SCScene flags=COPY_ON_WRITE source=VISIBILITY
graph_id_tag_update: id=OBCube flags=TRANSFORM, GEOMETRY, COPY_ON_WRITE source=VISIBILITY
graph_id_tag_update: id=MECube flags=LEGACY_0 source=VISIBILITY
graph_id_tag_update: id=MECube flags=COPY_ON_WRITE source=VISIBILITY
graph_id_tag_update: id=MAMaterial flags=COPY_ON_WRITE source=VISIBILITY
graph_id_tag_update: id=NTShader Nodetree flags=COPY_ON_WRITE source=VISIBILITY
graph_id_tag_update: id=NTShader Nodetree flags=COPY_ON_WRITE source=VISIBILITY
graph_id_tag_update: id=OBLight flags=TRANSFORM, GEOMETRY, COPY_ON_WRITE source=VISIBILITY
graph_id_tag_update: id=LALight flags=COPY_ON_WRITE source=VISIBILITY
graph_id_tag_update: id=OBCamera flags=TRANSFORM, GEOMETRY, COPY_ON_WRITE source=VISIBILITY
graph_id_tag_update: id=CACamera flags=COPY_ON_WRITE source=VISIBILITY
graph_id_tag_update: id=GRMaster Collection flags=COPY_ON_WRITE source=VISIBILITY
graph_id_tag_update: id=GRCollection flags=COPY_ON_WRITE source=VISIBILITY
graph_id_tag_update: id=WOWorld flags=COPY_ON_WRITE source=VISIBILITY
graph_id_tag_update: id=NTShader Nodetree flags=COPY_ON_WRITE source=VISIBILITY
graph_id_tag_update: id=NTShader Nodetree flags=COPY_ON_WRITE source=VISIBILITY
Depsgraph built in 0.001980 seconds.
graph_id_tag_update: id=SCScene flags=COPY_ON_WRITE source=VISIBILITY
graph_id_tag_update: id=OBCube flags=TRANSFORM, GEOMETRY, COPY_ON_WRITE source=VISIBILITY
graph_id_tag_update: id=MECube flags=LEGACY_0 source=VISIBILITY
graph_id_tag_update: id=MECube flags=COPY_ON_WRITE source=VISIBILITY
graph_id_tag_update: id=MAMaterial flags=COPY_ON_WRITE source=VISIBILITY
graph_id_tag_update: id=NTShader Nodetree flags=COPY_ON_WRITE source=VISIBILITY
graph_id_tag_update: id=NTShader Nodetree flags=COPY_ON_WRITE source=VISIBILITY
graph_id_tag_update: id=OBLight flags=TRANSFORM, GEOMETRY, COPY_ON_WRITE source=VISIBILITY
graph_id_tag_update: id=LALight flags=COPY_ON_WRITE source=VISIBILITY
graph_id_tag_update: id=OBCamera flags=TRANSFORM, GEOMETRY, COPY_ON_WRITE source=VISIBILITY
graph_id_tag_update: id=CACamera flags=COPY_ON_WRITE source=VISIBILITY
graph_id_tag_update: id=GRMaster Collection flags=COPY_ON_WRITE source=VISIBILITY
graph_id_tag_update: id=GRCollection flags=COPY_ON_WRITE source=VISIBILITY
graph_id_tag_update: id=WOWorld flags=COPY_ON_WRITE source=VISIBILITY
graph_id_tag_update: id=NTShader Nodetree flags=COPY_ON_WRITE source=VISIBILITY
graph_id_tag_update: id=NTShader Nodetree flags=COPY_ON_WRITE source=VISIBILITY
[SCScene :: View Layer]: Operation is entry point for update: PARAMETERS_EXIT()
[SCScene :: View Layer]: Operation is entry point for update: COPY_ON_WRITE()
[SCScene :: View Layer]: Operation is entry point for update: SOUND_EVAL()
[SCScene :: View Layer]: Operation is entry point for update: GEOMETRY_EVAL_DONE()
[SCScene :: View Layer]: Operation is entry point for update: TRANSFORM_FINAL()
[SCScene :: View Layer]: Operation is entry point for update: TRANSFORM_EVAL()
[SCScene :: View Layer]: Operation is entry point for update: TRANSFORM_INIT()
[SCScene :: View Layer]: Operation is entry point for update: PARAMETERS_EXIT()
[SCScene :: View Layer]: Operation is entry point for update: GEOMETRY_EVAL_INIT()
[SCScene :: View Layer]: Operation is entry point for update: COPY_ON_WRITE()
[SCScene :: View Layer]: Operation is entry point for update: COPY_ON_WRITE()
[SCScene :: View Layer]: Operation is entry point for update: TRANSFORM_SIMULATION_INIT()
[SCScene :: View Layer]: Operation is entry point for update: TRANSFORM_LOCAL()
[SCScene :: View Layer]: Operation is entry point for update: COPY_ON_WRITE()
[SCScene :: View Layer]: Operation is entry point for update: COPY_ON_WRITE()
[SCScene :: View Layer]: Operation is entry point for update: COPY_ON_WRITE()
[SCScene :: View Layer]: Operation is entry point for update: SCENE_EVAL()
[SCScene :: View Layer]: Operation is entry point for update: PARAMETERS_ENTRY()
[SCScene :: View Layer]: Operation is entry point for update: GEOMETRY_SELECT_UPDATE()
[SCScene :: View Layer]: Operation is entry point for update: COPY_ON_WRITE()
[SCScene :: View Layer]: Operation is entry point for update: SEQUENCES_EVAL()
[SCScene :: View Layer]: Operation is entry point for update: TRANSFORM_INIT()
[SCScene :: View Layer]: Operation is entry point for update: PARAMETERS_ENTRY()
[SCScene :: View Layer]: Operation is entry point for update: TRANSFORM_SIMULATION_INIT()
[SCScene :: View Layer]: Operation is entry point for update: COPY_ON_WRITE()
[SCScene :: View Layer]: Operation is entry point for update: COPY_ON_WRITE()
[SCScene :: View Layer]: Operation is entry point for update: TRANSFORM_FINAL()
[SCScene :: View Layer]: Operation is entry point for update: TRANSFORM_EVAL()
[SCScene :: View Layer]: Operation is entry point for update: TRANSFORM_INIT()
[SCScene :: View Layer]: Operation is entry point for update: COPY_ON_WRITE()
[SCScene :: View Layer]: Operation is entry point for update: TRANSFORM_LOCAL()
[SCScene :: View Layer]: Operation is entry point for update: PARAMETERS_EVAL()
[SCScene :: View Layer]: Operation is entry point for update: TRANSFORM_FINAL()
[SCScene :: View Layer]: Operation is entry point for update: COPY_ON_WRITE()
[SCScene :: View Layer]: Operation is entry point for update: GEOMETRY_EVAL()
[SCScene :: View Layer]: Operation is entry point for update: TRANSFORM_SIMULATION_INIT()
[SCScene :: View Layer]: Operation is entry point for update: GEOMETRY_EVAL()
[SCScene :: View Layer]: Operation is entry point for update: TRANSFORM_LOCAL()
[SCScene :: View Layer]: Operation is entry point for update: COPY_ON_WRITE()
[SCScene :: View Layer]: Operation is entry point for update: COPY_ON_WRITE()
[SCScene :: View Layer]: Operation is entry point for update: PARAMETERS_EVAL()
[SCScene :: View Layer]: Operation is entry point for update: VIEW_LAYER_EVAL()
[SCScene :: View Layer]: Operation is entry point for update: TRANSFORM_EVAL()
[SCScene :: View Layer]: Accumulated recalc bits for SCScene: 4282380163
[SCScene :: View Layer]: Accumulated recalc bits for OBCube: 8323
[SCScene :: View Layer]: Accumulated recalc bits for MECube: 4282380163
[SCScene :: View Layer]: Accumulated recalc bits for MAMaterial: 8320
[SCScene :: View Layer]: Accumulated recalc bits for NTShader Nodetree: 8320
[SCScene :: View Layer]: Accumulated recalc bits for OBLight: 8195
[SCScene :: View Layer]: Accumulated recalc bits for LALight: 8192
[SCScene :: View Layer]: Accumulated recalc bits for OBCamera: 8195
[SCScene :: View Layer]: Accumulated recalc bits for CACamera: 8192
[SCScene :: View Layer]: Accumulated recalc bits for GRMaster Collection: 8192
[SCScene :: View Layer]: Accumulated recalc bits for GRCollection: 8192
[SCScene :: View Layer]: Accumulated recalc bits for WOWorld: 8320
[SCScene :: View Layer]: Accumulated recalc bits for NTShader Nodetree: 8320
[SCScene :: View Layer]: deg_evaluate_copy_on_write on NTShader Nodetree (0x7f11e54e2338)
[SCScene :: View Layer]: deg_evaluate_copy_on_write on WOWorld (0x7f11e5af1a38)
[SCScene :: View Layer]: deg_evaluate_copy_on_write on GRMaster Collection (0x7f11e548dfb8)
[SCScene :: View Layer]: deg_evaluate_copy_on_write on CACamera (0x7f11e54e25b8)
[SCScene :: View Layer]: deg_evaluate_copy_on_write on OBCamera (0x7f11e8532638)
[SCScene :: View Layer]: deg_evaluate_copy_on_write on LALight (0x7f11e51279f8)
[SCScene :: View Layer]: deg_evaluate_copy_on_write on OBLight (0x7f11e8532038)
[SCScene :: View Layer]: deg_evaluate_copy_on_write on NTShader Nodetree (0x7f11e54e2838)
[SCScene :: View Layer]: deg_evaluate_copy_on_write on MAMaterial (0x7f11e548e138)
[SCScene :: View Layer]: deg_evaluate_copy_on_write on MECube (0x7f11e850d938)
[SCScene :: View Layer]: deg_evaluate_copy_on_write on OBCube (0x7f11e8523a38)
[SCScene :: View Layer]: deg_evaluate_copy_on_write on SCScene (0x7f11e5010438)
[SCScene :: View Layer]: deg_evaluate_copy_on_write on GRCollection (0x7f11e5af18b8)
[SCScene :: View Layer]: layer_eval_view_layer on View Layer (0x7f11e5af1eb8)
[SCScene :: View Layer]: BKE_object_eval_eval_base_flags on OBCube (0x7f11e8523a38)
[SCScene :: View Layer]: BKE_object_eval_eval_base_flags on OBCamera (0x7f11e8532638)
[SCScene :: View Layer]: BKE_object_eval_eval_base_flags on OBLight (0x7f11e8532038)
[SCScene :: View Layer]: BKE_nodetree_shading_params_eval on NTShader Nodetree (0x7f11e54e2338)
[SCScene :: View Layer]: BKE_world_eval on WOWorld (0x7f11e5af1a38)
[SCScene :: View Layer]: BKE_scene_eval_sequencer_sequences on SCScene (0x7f11e5010438)
[SCScene :: View Layer]: BKE_object_eval_local_transform on OBCamera (0x7f11e8532638)
[SCScene :: View Layer]: BKE_object_eval_local_transform on OBLight (0x7f11e8532038)
[SCScene :: View Layer]: BKE_object_eval_transform_final on OBLight (0x7f11e8532038)
[SCScene :: View Layer]: BKE_nodetree_shading_params_eval on NTShader Nodetree (0x7f11e54e2838)
[SCScene :: View Layer]: BKE_material_eval on MAMaterial (0x7f11e548e138)
[SCScene :: View Layer]: BKE_object_data_select_update on MECube (0x7f11e850d938)
[SCScene :: View Layer]: BKE_mesh_eval_geometry on MECube (0x7f11e850d938)
[SCScene :: View Layer]: BKE_object_eval_uber_data on OBCube (0x7f11e8523a38)
[SCScene :: View Layer]: BKE_object_handle_data_update on OBCube (0x7f11e8523a38)
[SCScene :: View Layer]: BKE_object_eval_transform_final on OBCamera (0x7f11e8532638)
[SCScene :: View Layer]: BKE_object_eval_local_transform on OBCube (0x7f11e8523a38)
[SCScene :: View Layer]: BKE_object_select_update on OBCube (0x7f11e8523a38)
[SCScene :: View Layer]: BKE_object_data_select_update on MECube (0x7f11cc80f738)
[SCScene :: View Layer]: BKE_object_eval_transform_final on OBCube (0x7f11e8523a38)