I noticed my node was not syncing, and through some debugging on #bitcoin-core-dev it seems like it was caused by running out of disk space which left the node in a desynced state, with the valid chain marked as invalid.

After freeing up some space and doing `reconsiderblock` it fixed it.

Comments from @sipa:

> Ugh. That is bad. Out of disk space should not result in database corruption.

> Database errors propagating up and being interpreted as (permanent) block invalidity was one of the contributing factors to the BDB/LevelDB fork in the 0.7/0.8 transition. 

logs:
```
2022-09-05T00:28:55Z UpdateTip: new best=000000000000000000087e337539b369b19570a88c493725020266387d22dac0 height=752167 version=0x2ce8e004 log2_work=93.70770
7 tx=761139817 date='2022-09-01T15:00:06Z' progress=0.998887 cache=146.8MiB(1101860txo)
2022-09-05T00:28:55Z Fatal LevelDB error: IO error: /home/jb55/.bitcoin/chainstate/2963623.ldb: No space left on device
2022-09-05T00:28:55Z You can use -debug=leveldb to get more complete diagnostic messages
2022-09-05T00:28:55Z *** System error while flushing: Fatal LevelDB error: IO error: /home/jb55/.bitcoin/chainstate/2963623.ldb: No space left on device
2022-09-05T00:28:55Z Error: A fatal internal error occurred, see debug.log for details
2022-09-05T00:28:56Z ERROR: ProcessNewBlock: ActivateBestChain failed (System error while flushing: Fatal LevelDB error: IO error: /home/jb55/.bitcoin/chains
tate/2963623.ldb: No space left on device)
2022-09-05T00:28:56Z ERROR: ConnectBlock: Consensus::CheckTxInputs: 221fa678c5c9953d6cd17e584f05c12ab10ba0f2fc8e8131e266f3f0e9819848, bad-txns-inputs-missing
orspent, CheckTxInputs: inputs missing/spent
2022-09-05T00:28:56Z InvalidChainFound: invalid block=000000000000000000079ba062298aa7cef1888f870c23e303a361c19b097ff8  height=752168  log2_work=93.707719  date=2022-09-01T15:13:42Z
2022-09-05T00:28:56Z InvalidChainFound:  current best=000000000000000000087e337539b369b19570a88c493725020266387d22dac0  height=752167  log2_work=93.707707  date=2022-09-01T15:00:06Z
2022-09-05T00:28:56Z ERROR: ConnectTip: ConnectBlock 000000000000000000079ba062298aa7cef1888f870c23e303a361c19b097ff8 failed, bad-txns-inputs-missingorspent, CheckTxInputs: inputs missing/spent
2022-09-05T00:28:56Z InvalidChainFound: invalid block=000000000000000000079ba062298aa7cef1888f870c23e303a361c19b097ff8  height=752168  log2_work=93.707719  date=2022-09-01T15:13:42Z
2022-09-05T00:28:56Z InvalidChainFound:  current best=000000000000000000087e337539b369b19570a88c493725020266387d22dac0  height=752167  log2_work=93.707707  date=2022-09-01T15:00:06Z
```

options.reindex = node::fReindex;
        options.reindex_chainstate = fReindexChainState;
        options.prune = chainman.m_blockman.IsPruneMode();
        options.check_blocks = args.GetIntArg("-checkblocks", DEFAULT_CHECKBLOCKS);
        options.check_level = args.GetIntArg("-checklevel", DEFAULT_CHECKLEVEL);
        options.require_full_verification = args.IsArgSet("-checkblocks") || args.IsArgSet("-checklevel");
        options.check_interrupt = ShutdownRequested;
        options.coins_error_cb = [] {
            uiInterface.ThreadSafeMessageBox(
                _("Error reading from database, shutting down."),
                "", CClientUIInterface::MSG_ERROR);
        };
        uiInterface.InitMessage(_("Loading block index…").translated);
        const auto load_block_index_start_time{SteadyClock::now()};
        auto catch_exceptions = [](auto&& f) {
            try {
                return f();
            } catch (const std::exception& e) {
                LogPrintf("%s\n", e.what());
                return std::make_tuple(node::ChainstateLoadStatus::FAILURE, _("Error opening block database"));
            }
        };
        auto [status, error] = catch_exceptions([&]{ return LoadChainstate(chainman, cache_sizes, options); });
        if (status == node::ChainstateLoadStatus::SUCCESS) {
            uiInterface.InitMessage(_("Verifying blocks…").translated);
            if (chainman.m_blockman.m_have_pruned && options.check_blocks > MIN_BLOCKS_TO_KEEP) {
                LogPrintfCategory(BCLog::PRUNE, "pruned datadir may not have more than %d blocks; only checking available blocks\n",
                                  MIN_BLOCKS_TO_KEEP);
            }
            std::tie(status, error) = catch_exceptions([&]{ return VerifyLoadedChainstate(chainman, options);});