Error - 'Conversion from string to type 'Date' is not valid.'

This can be caused by the language settings of your PC not matching the server. Effectively what happens is that the PC or the server presents a date that the other machine cannot translate into a known date.
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A typical example is where one side is set to US date settings and the other to the UK. When the day of the month goes beyond the 12th, you will see a problem. This is because, for example, one side will be presenting 15/11/2020 (UK format DDMMYYY) - while the other tries to read this as a US format (MMDDYYY) - as there is no 15th month in the year you receive an error because the system cannot set the date.
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Please ask your IT to check both your PC and that of the Server where ADM is running are both set to United Kingdom Date/time, rather than United States. Please ask that they check all areas of your operating system (including region settings), as well as all servers that are involved in the process (including IIS and SQL servers).
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This can also be the keyboard setting on the server is set to US, again this would need to be changed to UK.