Hello, I've been running BOINC for 5 years happily processing on GPU and CPU projects and all has been fine. I recently updated to Ubuntu Linux 18.0.4 LTS and then 20.0.4 LTS. BOINC version: 7.16.6 (x64)

Now BOINC does not download any GPU tasks for any GPU project, and I used to run multiple GPU projects. CPU tasks are downloaded and run fine. I completed removed and reinstalled BOINC and added just a single project as a test, Amicable Numbers, here's a copy of the Event log:

Fri 04 Feb 2022 08:10:54 AM EST | | Starting BOINC client version 7.16.6 for x86_64-pc-linux-gnu
Fri 04 Feb 2022 08:10:54 AM EST | | log flags: file_xfer, sched_ops, task
Fri 04 Feb 2022 08:10:54 AM EST | | Libraries: libcurl/7.68.0 OpenSSL/1.1.1f zlib/1.2.11 brotli/1.0.7 libidn2/2.2.0 libpsl/0.21.0 (+libidn2/2.2.0) libssh/0.9.3/openssl/zlib nghttp2/1.40.0 librtmp/2.3
Fri 04 Feb 2022 08:10:54 AM EST | | Data directory: /var/lib/boinc-client
Fri 04 Feb 2022 08:10:55 AM EST | | CUDA: NVIDIA GPU 0: NVIDIA GeForce GTX 1080 (driver version 470.86, CUDA version 11.4, compute capability 6.1, 4096MB, 3968MB available, 8876 GFLOPS peak)
Fri 04 Feb 2022 08:10:55 AM EST | | CUDA: NVIDIA GPU 1: NVIDIA GeForce GTX 1070 (driver version 470.86, CUDA version 11.4, compute capability 6.1, 4096MB, 3972MB available, 6463 GFLOPS peak)
Fri 04 Feb 2022 08:10:55 AM EST | | Creating new client state file
Fri 04 Feb 2022 08:10:55 AM EST | | libc: Ubuntu GLIBC 2.31-0ubuntu9.2 version 2.31
Fri 04 Feb 2022 08:10:55 AM EST | | Host name: home-linux
Fri 04 Feb 2022 08:10:55 AM EST | | Processor: 20 GenuineIntel Intel(R) Core(TM) i7-6950X CPU @ 3.00GHz [Family 6 Model 79 Stepping 1]
Fri 04 Feb 2022 08:10:55 AM EST | | Processor features: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx pdpe1gb rdtscp lm constant_tsc arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc cpuid aperfmperf pni pclmulqdq dtes64 monitor ds_cpl vmx est tm2 ssse3 sdbg fma cx16 xtpr pdcm pcid dca sse4_1 sse4_2 x2apic movbe popcnt tsc_deadline_timer aes xsave avx f16c rdrand lahf_lm abm 3dnowprefetch cpuid_fault epb cat_l3 cdp_l3 invpcid_single pti intel_ppin ssbd ibrs ibpb stibp tpr_shadow vnmi flexpriority ept vpid ept_ad fsgsbase tsc_adjust bmi1 hle avx2 smep bmi2 erms invpcid rtm cqm rdt_a rdseed adx smap intel_pt xsaveopt cqm_llc cqm_occup_llc cqm_mbm_total cqm_mbm_local dtherm ida arat pln pts md_clear flush_l1d
Fri 04 Feb 2022 08:10:55 AM EST | | OS: Linux Ubuntu: Ubuntu 20.04.3 LTS [5.3.0-7648-generic|libc 2.31 (Ubuntu GLIBC 2.31-0ubuntu9.2)]
Fri 04 Feb 2022 08:10:55 AM EST | | Memory: 31.20 GB physical, 4.00 GB virtual
Fri 04 Feb 2022 08:10:55 AM EST | | Disk: 224.67 GB total, 201.25 GB free
Fri 04 Feb 2022 08:10:55 AM EST | | Local time is UTC -5 hours
Fri 04 Feb 2022 08:10:55 AM EST | | Config: GUI RPCs allowed from:
Fri 04 Feb 2022 08:10:55 AM EST | | No general preferences found - using defaults
Fri 04 Feb 2022 08:10:55 AM EST | | Reading preferences override file
Fri 04 Feb 2022 08:10:55 AM EST | | Preferences:
Fri 04 Feb 2022 08:10:55 AM EST | | max memory usage when active: 15976.40 MB
Fri 04 Feb 2022 08:10:55 AM EST | | max memory usage when idle: 28757.52 MB
Fri 04 Feb 2022 08:10:55 AM EST | | max disk usage: 201.15 GB
Fri 04 Feb 2022 08:10:55 AM EST | | don't use GPU while active
Fri 04 Feb 2022 08:10:55 AM EST | | suspend work if non-BOINC CPU load exceeds 25%
Fri 04 Feb 2022 08:10:55 AM EST | | (to change preferences, visit a project web site or select Preferences in the Manager)
Fri 04 Feb 2022 08:10:55 AM EST | | Setting up project and slot directories
Fri 04 Feb 2022 08:10:55 AM EST | | Checking active tasks
Fri 04 Feb 2022 08:10:55 AM EST | | Setting up GUI RPC socket
Fri 04 Feb 2022 08:10:55 AM EST | | gui_rpc_auth.cfg is empty - no GUI RPC password protection
Fri 04 Feb 2022 08:10:55 AM EST | | Checking presence of 0 project files
Fri 04 Feb 2022 08:10:55 AM EST | | This computer is not attached to any projects
Fri 04 Feb 2022 08:10:55 AM EST | | Suspending GPU computation - computer is in use
Fri 04 Feb 2022 08:14:51 AM EST | | Fetching configuration file from https://sech.me/boinc/Amicable/get_project_config.php
Fri 04 Feb 2022 08:15:12 AM EST | Amicable Numbers | Fetching scheduler list
Fri 04 Feb 2022 08:15:13 AM EST | Amicable Numbers | Master file download succeeded
Fri 04 Feb 2022 08:15:18 AM EST | Amicable Numbers | Sending scheduler request: Project initialization.
Fri 04 Feb 2022 08:15:18 AM EST | Amicable Numbers | Requesting new tasks for CPU and NVIDIA GPU
Fri 04 Feb 2022 08:15:19 AM EST | Amicable Numbers | Scheduler request completed: got 0 new tasks
Fri 04 Feb 2022 08:15:19 AM EST | Amicable Numbers | No tasks sent
Fri 04 Feb 2022 08:15:19 AM EST | Amicable Numbers | Tasks for CPU are available, but your preferences are set to not accept them
Fri 04 Feb 2022 08:15:19 AM EST | Amicable Numbers | Tasks for AMD/ATI GPU are available, but your preferences are set to not accept them
Fri 04 Feb 2022 08:15:19 AM EST | Amicable Numbers | Project requested delay of 7 seconds
Fri 04 Feb 2022 08:15:19 AM EST | | General prefs: from http://boinc.bakerlab.org/rosetta/ (last modified 03-Aug-2017 22:29:21)
Fri 04 Feb 2022 08:15:19 AM EST | | Host location: none
Fri 04 Feb 2022 08:15:19 AM EST | | General prefs: using your defaults
Fri 04 Feb 2022 08:15:19 AM EST | | Reading preferences override file
Fri 04 Feb 2022 08:15:19 AM EST | | Preferences:
Fri 04 Feb 2022 08:15:19 AM EST | | max memory usage when active: 15976.40 MB
Fri 04 Feb 2022 08:15:19 AM EST | | max memory usage when idle: 28757.52 MB
Fri 04 Feb 2022 08:15:19 AM EST | | max disk usage: 200.26 GB
Fri 04 Feb 2022 08:15:19 AM EST | | suspend work if non-BOINC CPU load exceeds 25%
Fri 04 Feb 2022 08:15:19 AM EST | | (to change preferences, visit a project web site or select Preferences in the Manager)
Fri 04 Feb 2022 08:15:19 AM EST | | Resuming GPU computation
Fri 04 Feb 2022 08:15:29 AM EST | Amicable Numbers | Sending scheduler request: To fetch work.
Fri 04 Feb 2022 08:15:29 AM EST | Amicable Numbers | Requesting new tasks for NVIDIA GPU
Fri 04 Feb 2022 08:15:30 AM EST | Amicable Numbers | Scheduler request completed: got 0 new tasks
Fri 04 Feb 2022 08:15:30 AM EST | Amicable Numbers | Project requested delay of 7 seconds
Fri 04 Feb 2022 08:28:44 AM EST | Amicable Numbers | Sending scheduler request: To fetch work.
Fri 04 Feb 2022 08:28:44 AM EST | Amicable Numbers | Requesting new tasks for NVIDIA GPU
Fri 04 Feb 2022 08:28:46 AM EST | Amicable Numbers | Scheduler request completed: got 0 new tasks
Fri 04 Feb 2022 08:28:46 AM EST | Amicable Numbers | Project requested delay of 7 seconds
Fri 04 Feb 2022 08:38:59 AM EST | Amicable Numbers | Sending scheduler request: To fetch work.
Fri 04 Feb 2022 08:38:59 AM EST | Amicable Numbers | Requesting new tasks for NVIDIA GPU
Fri 04 Feb 2022 08:39:01 AM EST | Amicable Numbers | Scheduler request completed: got 0 new tasks
Fri 04 Feb 2022 08:39:01 AM EST | Amicable Numbers | Project requested delay of 7 seconds

When I first started BOINing, like five years ago I had to add the GPU flag in the cc_config.xml file. I repeated this step, "use_all_gpus" as shown below:

<cc_config>
<log_flags>
<task>1</task>
<file_xfer>1</file_xfer>
<sched_ops>1</sched_ops>
<use_all_gpus>1</use_all_gpus>
</log_flags>
</cc_config>

However GPU tasks are still no downloading. I would appreciate assistance, thanks a lot!

The Amicable Numbers applications page shows that their GPU programs are written using the OpenCL programming language.

Your event log shows no sign of an OpenCL driver - only CUDA. Try to add an NVidia OpenCL component to your existing driver package. You'll probably have to reboot for it to be recognised by BOINC.

Thank you, I'll try this!

Thanks again! After installing OpenCL I'm back up and running Amicable, Milkyway and my other GPU projects!

Always nice when things go right!