Actually, today it does work again, so there is no solution yet. Yesterday a company with more than 10 users worked normally, but today it does not work again. They have windows 10.

I watched the customer via remote:
Customer got the enabler, then immediately tried to export the NL>>exports>>accumulated PL and it worked. After half a minute he could do the same export.

There are a lot of these in the server log.
2020-02-14 11:48:22 /THREAD(5) Error: Failed registering upload job
2020-02-14 11:48:35 /THREAD(5) *** Uploading backup D:\Backup\TB.TXT to cloud storage ***

client log:
2020-02-14 11:54:05 *** Using Clock Replacement ***
2020-02-14 11:54:05 *** using a freelist to keep track of free space ***
2020-02-14 11:54:05 enabler flag 2 set by using PACKFIELDMATRIX in halcust\Import70to81.hal:497
2020-02-14 11:54:06 Database ID is: 8B176FEBCF6B342E8F15B55CCEC63953
2020-02-14 11:54:06 aiting for HAL threads to finish connecting to server failed to setup connect
2020-02-14 11:54:06 connecting to server C5F9AD6B-586F4267-CED847CC-A82F177F-EBCAC167@10.20.205.15
2020-02-14 11:54:08 8.5 2020-01-07 (build 85330517)

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