"flock failed to lock maps file: errno = 35"

I've been developing on my iMAC for several months, tonight for some reason I'm not getting two of these:
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2020-11-08 16:57:05.191094+0000 mdFileIO[1305:17055] flock failed to lock maps file: errno = 35
2020-11-08 16:57:05.194216+0000 mdFileIO[1305:17055] flock failed to lock maps file: errno = 35

I've read elsewhere that rebooting fixes this, which it did, but it comes back. What is this caused by?

My system:
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iMac (Retina 5K, 27-inch, Late 2015)
Processor 4 GHz Quad-Core Intel Core i7
Memory 16 GB 1867 MHz DDR3
Graphics AM Radeon R9 M395X 4 GB

Xcode:
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Version 12.1 (12A7403)

Qt Creator:
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Qt Creator 4.13.2
Based on Qt 5.15.1 (Clang 11.0 (Apple), 64 bit)
Built on Oct 1 2020 01:16:45
From revision 2ee1af2032

Kits:
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Desktop Qt 5.15.0 clang 64bit

Compilers:
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C, Clang (C, x84 64bit in /usr/bin)

Same issue. Look forward to others reply it.
"flock failed to lock maps file: errno = 35"
 
 
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